Glimm-Lacy_Botany Illustrated 2nd ed.pdf - Index of

Janice Glimn-Lacy 

6810 Shadow Brook Court 

Indianapolis, IN 46214-1901 

USA 

janglimn@umich.edu 

Library of Congress Control Number: 2005935289 

ISBN-10: 0-387-28870-8 eISBN: 0-387-28875-9 

ISBN-13: 978-0387-28870-3 

Printed on acid-free paper. 

Peter B. Kaufman 

Department of Molecular, Cellular, and 

Developmental Biology 

University of Michigan 

Ann Arbor, MI 48109-1048 

USA 

pbk@umich.edu 

C○ 2006 Janice Glimn-Lacy and Peter B. Kaufman 

All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer 

Science+Business Media, Inc., 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly 

analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar 

methodology now known or hereafter developed is forbidden. 

The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken 

as an expression of opinion as to whether or not they are subject to proprietary rights. 

Printed in the United States of America. (TB/MVY) 

987654321 

springer.com

Preface 

This is a discovery book about plants. It is for everyone 

interested in plants including high school and college/ 

university students, artists and scientific illustrators, 

senior citizens, wildlife biologists, ecologists, professional 

biologists, horticulturists and landscape designers/architects, 

engineers and medical practitioners, and 

physical therapists and their patients. Here is an opportunity 

to browse and choose subjects of personal interest, 

to see and learn about plants as they are described. 

By adding color to the drawings, plant structures become 

more apparent and show how they function in 

life. The color code clues tell how to color for definition 

and an illusion of depth. For more information, the text 

explains the illustrations. The size of the drawings in 

relation to the true size of the structures is indicated 

by × 1 (the same size) to × 3000 (enlargement from 

true size) and × n/n (reduction from true size). 

The contents reflect a balanced selection of botanical 

subject matter with emphasis on flowering plants, 

the dominant plants of the earth. After a page about 

plant names and terms, the book is divided into three 

sections. The first is an introduction to plants, showing 

structure and function; then, major groups, providing 

an overview of the diverse forms; and lastly, oneseventh 

of the flowering plant families, with the accent 

on those of economic importance. The sequence in the 

sections is simple to complex (cell to seed), primitive to 

advanced (blue-greens to flowering plants), and unspecialized 

to specialized (magnolias to asters and waterplantains 

to orchids). Where appropriate, an “of interest” 

paragraph lists ways these genera are relevant in 

our lives (categories include use as food, ornamentals, 

lumber, medicines, herbs, dyes, fertilizers; notice of wild 

or poisonous; and importance in the ecosystem). “Of 

interest” sections in Botany Illustrated, second edition, 

have been expanded to include many more topics of 

interest. 

Evolutionary relationships and the classification of 

plants have been undergoing many changes in the past 

two decades since the first edition. In this edition controversial 

categories have been eliminated allowing individuals 

to be exposed to current thinking on plant classification. 

Classification from this second edition may 

be found in the Index under “Fungi Kingdom” and “Plant 

Kingdom.” Pages on bacteria have been eliminated and 

two new pages on plant fossils, with accompanying illustrations, 

have been added. Every text page has undergone 

extensive revision. 

For those interested in the methods used and the 

sources of plant materials in the illustrations, an explanation 

follows. For a developmental series of drawings, 

there are several methods. One is collecting several 

specimens at one time in different stages of development; 

for example, several buds and flowers of a plant 

(see 29) and button to mature forms of mushrooms (see 

50, 51). Then, some are cut open to observe parts and 

decide how to present them, while others are to use for 

final drawings. Another method is waiting for the plant to 

change, which involves “forcing” stems (see 14), germinating 

seeds (see 40), watching one leaf expand (see 

69), and drawing a flower in one season and its mature 

fruit in another (see 104, 109, 110, 111). An alternative 

to waiting for fruit is to use a collection of dry or frozen 

specimens, so that as spring flowers appear, the later 

maturing fruits can be seen at the same time (see 102, 

105, 106). 

In the first section, introduction to plants, there are several 

sources for various types of drawings. Hypothetical 

diagrams show cells, organelles, chromosomes, 

the plant body indicating tissue systems and experiments 

with plants, and flower placentation and reproductive 

structures. For example, there is no average or 

standard-looking flower; so, to clearly show the parts 

of a flower (see 27), a diagram shows a stretched out 

and exaggerated version of a pink (Dianthus) flower 

(see 87). A basswood (Tilia) flower is the basis for 

diagrams of flower types and ovary positions (see 

28). Another source for drawings is the use of prepared 

microscope slides of actual plant tissues. Some 

are traced from microscope slide photographs such 

as cross-sections, vascular bundles, and transections. 

Scanning and transmission electron micrographs are 

traced for chloroplasts, amyloplasts, trichomes, internodes, 

and pollen grains. Preserved museum specimens 

provide the source for animals in the pollination series. 

The remainder of the drawings are from actual plants 

found in nature, the grocery store, plant nurseries, farm 

fields, botanical gardens, florist shops, and suburban 

yards. 

In the major groups section, three pages have hypothetical 

diagrams, indicated in the captions. Other microscopic 

forms are from observations of living material or 

prepared microscope slides. For plants not locally available, 

dry-pressed herbarium specimens are measured 

for drawings (Stylites, Helminthostachys, Gnetum, and 

Ephedra) or machine-copied and traced (habit drawings 

v

of filamentous algae) or chemically revived to three 

dimensions (bryophytes) for drawing with the use of 

a dissecting microscope. Drawings are also made 

from liquid-preserved specimens (Tmesipteris habit, 

Welwitschia and Ginkgo reproductive structures). For 

the majority of this section’s drawings (including Welwitschia 

habit), living organisms are used. 

vi 

For the flowering plant families section, except for two 

indicated diagrams in the grass family, all the drawings 

are from actual plants gleaned from fields, forests, roadside 

ditches, bogs, neighbors’ yards, botanical conservatories, 

florist shops, grocery stores, and our gardens. 

The bumblebee arrived of its own accord. 

Janice Glimn-Lacy 

Peter B. Kaufman

Color Code Clues 

The illustrations may be colored by using the easy-tofollow 

Color Code. Each drawing has lines from structures 

to letters, duplicated in the Color Code. All structures 

similar to the one with a line and letter are the 

same color; for example, only one of five petals may be 

identified. Colored pencils are recommended for pleasing 

results. My personal preference is Berol Prismacolor 

pencils. The colors needed are 2 shades of red, 

green, and blue, and 1 each of orange, yellow, pink, 

purple, brown, and black. Sometimes the Color Code 

lists double colors such as yellow-green, red-brown, or 

purple-green. Color the same area with a light touch of 

both colors for the closest resemblance to the plant’s 

natural color. A black pencil used lightly provides a gray 

color. White is to remain blank. Using pink over light 

purple results in a lavender color. So as not to color 

areas that are to remain white or have small areas of 

color, follow the order listed in the Color Code foranindividual 

drawing. Letters, missing from the Color Code, 

are in the text. They usually indicate structures shown 

as black outlines or colorless areas. 

When drawing a 3-dimensional object, scientific illustrators 

traditionally use an upper-left light source on the 

object, which casts shadows on the lower right. Converting 

those shadows into ink dots (stipple) and lines 

(hatch) within the drawing outline creates an illusion of 

depth. Another aid to realism in black-and-white drawings 

is to show foreground structures as darker and 

larger than background ones. Obvious examples using 

this technique are the pitcher-plant leaves (see 91) 

and the iris flower and leaves (see 129). We see colored 

objects as brighter and more distinct when near 

and as muted and less distinct when distant. Accordingly, 

by the use of bright shades of colors for foreground 

structures and muted shades for background 

structures, your colored pictures will appear more 3dimensional. 

Darker shades of a color on the dot-andline 

shadow areas will add to the effect. 

To avoid having a green book, the illustration of foliage 

has been kept to a minimum with an abundant variety 

of colors indicated throughout. In the introduction to 

plants section, there is uniformity of a designated color. 

For example, water-conducting tissue and cells (xylem) 

are always color-coded blue, so that as you look at your 

colored pages, you see how water moves within a plant. 

For enlarged flower drawings in the flowering plant families 

section, true colors of flower parts are indicated in 

the Color Code. Dotted lines indicate where structures 

have been cut, show “see-through” areas, or separate 

color areas. Some lines are close together, others are 

single lines to color, but a color overlap of the lines will 

not detract from the over-all result. 

Begin with the first page, which explains the names 

used, then choose any page that strikes your interest. 

If a flowering plant structure is new to you, it would be 

most helpful to look over the structure of the stem (14), 

leaf (21, 23), flower (27, 28), and fruit types (38, 39). 

Then, you will be ready to explore. Some discoveries 

are seeing how an apple flower matures into an apple 

(see 99), finding that grape flowers have flip-top petal 

caps (see 104), and learning that inside a common garden 

sage flower is a mechanical “arm” for sticking pollen 

on visiting bees (see 113). 

vii

Acknowledgements 

We wish to thank the following colleagues of The University 

of Michigan for their contribution and review of 

specific topics: Dr. Joseph Beitel, lycopods; Dr. Michael 

Carleton, bats; Dr. Allen Fife, lichens; Dr. Michael Huft, 

euphorbs; Dr. Thomas Rosatti, heaths; Dr. Ann Sakai, 

maples; Dr. Alan Simon, birds; Dr. Wm. Wayt Thomas, 

sedges; Dr. Kerry S. Walter, orchids. Also, we would 

like to thank the following University of Michigan Botany 

Faculty in the Department of Botany (now, Department 

of Ecology and Evolutionary Biology and Department 

of Molecular, Cellular, and Developmental Biology); 

Dr. Howard Crum, bryophytes; Dr. Harry Douthit, 

bacteria; Dr. Robert Shaffer, fungi; Dr. William R. Taylor, 

algae; Dr. Edward G. Voss, grasses; and Dr. Warren H. 

Wagner, Jr., ferns, plus access to his extensive plant 

collections; the staffs of the University Herbarium, Museum 

of Natural History and University Science Library 

for advice, loans of resource materials, use of 

microscopes, books and other printed materials. Dr. P. 

Dayananadan was especially generous with his excellent 

scanning electron micrographs. For assistance in 

obtaining rare and out-of-season living plants, we thank 

William Collins, Jane LaRue, and Patricia Pachuta of 

the University of Michigan Matthaei Botanical Gardens. 

We also thank Dr. David Darby of the University of 

Minnesota for his review of geological information. For 

palms, we thank Dr. Ackerman of the Garfield Conservatory, 

Chicago. For locating regional plants, we appreciate 

the assistance of Robert Anderson, Patricia and 

Terrance Glimn, Marie Mack, Lorraine Peppin, Ellen 

Weatherbee, and Catherine Webley. Also, we wish to 

thank Dr. Peter Carson, Dr. Tomas Carlson, Dr. Michael 

Christianson, Dr. Michael Evans, Dr. Jack Fisher, and 

Dr. James Wells. 

For reviewing the text format and page design, reading 

and coloring sample pages, and suggesting many 

helpful changes, we thank the 80 beginning biology 

students of James Lenic and James Potoczak of the 

West High School, Garden City, Michigan, 1980, and 

the 93 practical botany students of Dr. Eric Steiner, Dr. 

Kit Streusand, Dr. Lucinda Thompson, Dr. Gay Troth, 

and Dr. James Winsor of the University of Michigan. 

From the School of Art and Design at The University 

of Michigan, we are indebted to Douglas Hesseltine for 

book design suggestions, to Duane Overmyer for typography 

lessons, and William L. Brudon as both instructor 

of biological illustration and as an advisor and friend. 

Belatedly, we wish to gratefully thank our editor at Van 

Nostrand & Reinhold, Susan Munger, for the first edition. 

Now with the publication of the second edition, we 

wish to wholeheartedly thank our editors Jacco Flipsen, 

Keri Witman, and Shoshana Sternlicht at Springer. Also, 

many thanks to Robert Maged and his Springer production 

staff. 

Lastly, we express our special appreciation to our 

families—Jack, John, and Jim Lacy and Hazel, Linda, 

and Laura Kaufman. 

ix

Contents 

v Preface 

vii Color Code Clues 

ix Acknowledgements 

Introduction to Plants 

1 Names and Terms 

2 Cell Structure 

3 Cell Organelles 

4 Cell Pigments 

5 Cell—Water Movement 

6 Cell Chromosomes 

7 Cell—Mitosis 

8 Cell Types 

9 Tissue Systems of the Plant Body 

10 Tissue—Epidermis 

11 Tissue—Primary Vascular System 

12 Root Types and Modifications 

13 Root Tissues 

14 Stem Structure 

15 Stem Tissues 

16 Stem Modifications 

17 Stem—Water Transport 

18 Stem—Food Transport 

19 Stem—Apical Dominance 

20 Stem—Growth Movements 

21 Leaf Types and Arrangement 

22 Leaf Tissues 

23 Leaf Modifications 

24 Leaf—Photosynthesis 

25 Leaf—Nutrient Deficiency Symptoms 

26 Flower Initiation in Response to Daylength 

27 Flower Structure 

28 Flower Structure Variations 

29 Flower Development 

30 Flower—Meiosis 

31 Flower—Pollen Development 

32 Flower—Ovule Development 

33 Flower Pollination by Insects 

34 Flower Pollination by Insects (continued) 

xi

35 Flower Pollination by Wind 

36 Flower Pollination by Birds and Bats 

37 Flower—Fertilization and Embryo Development 

38 Fruit—Dry Types 

39 Fruit—Fleshy Types, Compound 

40 Seed Structure and Germination 

Major Groups 

41 Major Groups; Geologic Time Scale 

42 Fossils 

43 Fossils (continued) 

44 Blue-greens 

45 Slime Molds 

46 Water Molds, Downy Mildews, White Rusts; Chytrids and Allies 

47 Fungi 

48 Molds, Mildews, Morels (Sac Fungi) 

49 Rusts, Smuts, Jelly Fungi (Club Fungi) 

50 Gill Fungi 

51 Gill and Pore Fungi 

52 Pore, Coral and Toothed Fungi 

53 Puffballs, Stinkhorns, Bird’s-nest Fungi 

54 Lichens 

55 Dinoflagellates 

56 Golden Algae, Yellow-green Algae, Diatoms 

57 Red Algae 

58 Green Algae 

59 Brown Algae 

60 Brown Algae (continued) 

61 Brown Algae (continued) 

62 Stoneworts 

63 Liverworts, Hornworts, Mosses 

64 Whisk Ferns 

65 Clubmosses, Spikemosses, Quillworts 

66 Horsetails 

67 Ferns 

68 Common Ferns 

69 Fern Leaf Development 

70 Water Ferns 

71 Cycads 

72 Ginkgo 

73 Conifers 

74 Gnetes 

xii

75 Flowering Plant Classification 

76 Major Land Plant Communities 

Flowering Plant Families 

Dicotyledons 

77 Magnolia Family (Magnoliaceae) 

78 Laurel Family (Lauraceae) 

79 Water Lily Family (Nymphaeaceae) 

80 Buttercup Family (Ranunculaceae) 

81 Witch Hazel Family (Hamamelidaceae) 

82 Elm Family (Ulmaceae) 

83 Beech Family (Fagaceae) 

84 Birch Family (Betulaceae) 

85 Cactus Family (Cactaceae) 

86 Cactus Family (continued) 

87 Pink Family (Caryophyllaceae) 

88 Goosefoot Family (Chenopodiaceae) 

89 Buckwheat Family (Polygonaceae) 

90 Mallow Family (Malvaceae) 

91 Pitcher-Plant Family (Sarraceniaceae) 

92 Violet Family (Violaceae) 

93 Begonia Family (Begoniaceae) 

94 Gourd Family (Cucurbitaceae) 

95 Willow Family (Salicaceae) 

96 Mustard Family (Brassicaceae) 

97 Heath Family (Ericaceae) 

98 Saxifrage Family (Saxifragaceae) 

99 Rose Family (Rosaceae) 

100 Pea Family (Fabaceae) 

101 Dogwood Family (Cornaceae) 

102 Staff-tree Family (Celastraceae) 

103 Spurge Family (Euphorbiaceae) 

104 Grape Family (Vitaceae) 

105 Maple Family (Aceraceae) 

106 Cashew Family (Anacardiaceae) 

107 Rue Family (Rutaceae) 

108 Geranium Family (Geraniaceae) 

109 Carrot Family (Apiaceae) 

110 Milkweed Family (Asclepiadaceae) 

111 Nightshade Family (Solanaceae) 

112 Morning Glory Family (Convolvulaceae) 

113 Mint Family (Lamiaceae) 

xiii

114 Olive Family (Oleaceae) 

115 Figwort Family (Scrophulariaceae) 

116 Gesneria Family (Gesneriaceae) 

117 Honeysuckle Family (Caprifoliaceae) 

118 Teasel Family (Dipsacaceae) 

119 Aster Family (Asteraceae) 

Monocotyledons 

120 Water-plantain Family (Alismataceae) 

121 Spiderwort Family (Commelinaceae) 

122 Sedge Family (Cyperaceae) 

123 Grass Family (Poaceae) 

124 Arrowroot Family (Marantaceae) 

125 Palm Family (Arecaceae) 

126 Palm Family (continued) 

127 Arum Family (Araceae) 

128 Lily Family (Liliaceae) 

129 Iris Family (Iridaceae) 

130 Orchid Family (Orchidaceae) 

131 Bibliography 

133 Glossary of Word Roots, Metric Equivalents 

135 Index 

xiv

About the Authors 

Janice Glimn-Lacy has a Bachelor of Science in Botany from The University of Michigan, 

1973, and plans to have a Bachelor of Fine Arts from Herron School of Art and Design, Indiana 

University-Purdue University at Indianapolis (IUPUI), 2008. She is a member of the University of 

Michigan Alumni Association, the Indiana Native Plant and Wildflower Society, the Indianapolis 

Museum of Art, the Indianapolis Museum of Art Horticultural Society, and the Watercolor Society 

of Indiana. While a Landscape Designer, she wrote and illustrated What Flowers When with 

Hints on Home Landscaping (the Flower and the Leaf, Indianapolis, 1995). She was a co-author 

and illustrator of Practical Botany (Reston), illustrator of Michigan Trees (University of Michigan 

Press), Plants Their Biology and Importance (Harper & Row), several Ph.D. theses, and many 

botanical journal articles. For several years she taught botanical illustration in the University 

of Michigan Adult Education Program, at the Indianapolis Art Center, and at the Indianapolis 

Museum of Art. 

Peter B. Kaufman, Ph.D. Botany, obtained degrees at Cornell University and the University of 

California, Davis. A plant physiologist, now Professor Emeritus of Biology, and currently, Senior 

Research Scientist in the University of Michigan Integrative Medicine Program (MIM), he has 

been at the University of Michigan since 1956. He is a Fellow of the American Association for 

the Advancement of Science (AAAS). He is past President of the Michigan Botanical Club, past 

Chairman of the Michigan Natural Areas Council, a co-author of Practical Botany (Reston), Plants, 

People and Environment (Macmillan), Plants Their Biology and Importance (Harper & Row), 

Creating a Sustainable Future, Living in Harmony With the Earth (Researchco Book Center), 

Natural Products from Plants (CRC Press)/Taylor and France’s Group, LLC, Handbook of Molecular 

and Cellular Methods in Biology and Medicine (CRC Press), Methods in Gene Biotechnology 

(CRC Press), and the author of numerous articles in botanical journals. He hosted a 20-part educational 

TV series ‘The House Botanist ’ (University of Michigan) and twice was a guest on ABC’s 

program ‘Good Morning America’ to talk on gardening topics.

Names and Terms 

Division. The major category is called a division 

and is equivalent to phylum in the animal kingdom. 

Division name endings indicate plants (-phyta) and 

fungi (-mycota). In the top illustration are some examples 

of Magnoliophyta, the flowering plant division. The 

endings of lesser categories indicate class (-opsida), 

subclass (-idea), order (-ales), and family (-aceae). 

Classification of one specific plant is shown. 

Class. Flowering plants are divided into 2 classes: 

Magnoliopsida, the dicots (2 seed leaves), and Liliopsida, 

the monocots (1 seed leaf). A seed leaf is the first 

leaf to emerge from an embyro in the seed (see 40). In 

the second illustration are examples of Liliopsida, the 

monocot class. 

Family. The third group of plants shows some monocots 

in the lily family, Liliaceae (see 128). 

Genus Species. Next are 3 lilies in the genus 

Lilium. A plant type is given a 2-part scientific name – a 

generic name, the genus, which is a noun and is always 

capitalized, and a specific epithet, the species, which 

is usually an adjective. For example officinalis means 

medicinal and is commonly used for herbs. Sometimes 

a species is named for a person. A species that is not 

named is written as sp. (plural: spp.). 

In a written list of species in the same genus, it is 

only necessary to fully write the genus once at the beginning. 

The genus of species that follow is indicated 

with the first letter of the genus followed by a period. 

For example: Mammillaria albescens, M. bocasana, 

M. columbiana. 

The 2 parts of the name, called a binomial, are italicized 

in print and underlined when handwritten. The 

binomial is sometimes followed by a name abbreviation 

of the person who first described the plant in botanical 

literature. For example, the most common is Linnaeus, 

the Swedish botanist, indicated by an L. 

One of the reasons the scientific name of a plant may 

change is because it is discovered that someone else 

named the plant earlier. The newly found name is published 

in Latin. Another reason a name may change 

is that the plant is reclassified into a different group. 

There may also be many forms of a plant with separate 

species names, when later, it is decided they are all the 

same species. 

1 

The specific lily here is Lilium michiganense, with the 

English common name Michigan Lily. A spontaneously 

occurring variation of a species in nature also may have 

a variety (var.) name (see 101). An X between the 

genus and new specific epithet (see 77) indicates a hybrid 

between 2 species. Hybrids may occur in nature or 

be derived by plant breeding. Intergeneric hybrids have 

a combined name of the genera with a capital X at the 

beginning. For example, X Heucherella is a hybrid between 

Herchera (pink to red flowers) and Tiarella (white 

flowers) and has pale pink flowers. 

Common Names. As names differ from region to region, 

a plant may have many common names. For 

example, Amelanchier may be commonly named serviceberry, 

shadbush, or June-berry. Sometimes a common 

name is used for unrelated plants. So to be universally 

understood, botanists use the binomial system of 

naming plants in Latin. A plant variety that exists only 

through cultivation has a common cultivar name (cv., 

cultivated variety) (see 93). 

Habit vs. Habitat. The gross habit refers to the appearance 

of an individual plant in its entirety. Where 

a plant grows in its environment is called the habitat, 

such as a beech-maple forest, a pond, a prairie, or a 

desert. 

Herbaceous vs. Woody. Herbs have little or no secondary 

vascular tissues and their above-ground shoots 

usually die back at the end of the growing season. Herbs 

are considered to be more advanced in evolution than 

woody plants (shrubs and trees) with secondary vascular 

tissues (secondary xylem and phloem) present, 

which persists in growth year after year in stems and 

roots. 

Macroscopic vs. Microscopic. If a plant structure can 

be seen with the unaided eye, it is designated macroscopic; 

if a microscope is used to observe it, it is microscopic 

in size. 

COLOR CODE 

orange: tepals (a) (see 27) 

brown: stamens (b) 

light green: stigma (c) 

green: peduncle (d), leaves (e), stem (f)

Cell Structure 

Parts of a Cell 

Cell Wall. The cell wall (a) encloses and protects the 

cell contents and plays a vital role in cell division and 

cell expansion. Composed of overlapping cellulose microfibrils, 

other polysaccharides and varying amounts 

of lignin, the cell wall is a relatively rigid structure in mature 

cells. It may vary in thickness and has pits that that 

function in communication between cells. The region 

between the primary walls of adjacent cells, the middle 

lamella (b), is composed of a cementing substance 

called pectin. 

Other substances that may be present in the cell wall 

are gums, resins, silica, calcium carbonate, waxes and 

cutin, and both structural protein and enzymes (which 

are also proteins). There may be intercellular spaces 

(c) between walls of bordering cells. 

Pits. Primary pit fields (d) are thin areas in the cell wall 

with tiny strands of cytoplasm, called plasmodesmata 

(s), connecting one cell with another. Pits are important 

in facilitating the flow of water and mineral nutrients between 

conducting cells in the xylem vascular tissue (see 

11). 

Plasma Membrane. A semipermeable membrane (e) 

encloses the cytoplasm within a cell. It is composed 

of variable amounts of fat type molecules (lipids) and 

proteins, and has within it channels for the movement 

of ions such as potassium (K + ), calcium (Ca 2 + ), and 

hydrogen (H + ). 

Cytoplasm. The cytoplasm (cytosol, f) is a liquid, gellike 

substance and contains several types of organelles; 

smooth (g) or rough endoplasmic reticulum (h), rough 

referring to attached ribosomes (i) on the ER (endoplasmic 

reticulum) and free ribosomes. 

Vacuole. In a mature plant cell, one large vacuole usually 

occupies most of the space within the cell. It is sur- 

2 

rounded by a single-layered membrane, the tonoplast 

(j), and contains cell sap composed of water, sugars, 

and various organic and inorganic solutes. It may, in 

some cells such as in beet roots and flower petals, contain 

water-soluble pigments. The vacuole functions in 

regulation of osmotic balance and turgidity of the cell, 

and it stores secondary metabolites. 

Organelles. Within the cytoplasm are mitochrondria 

(k), dictyosomes (Golgi bodies), microbodies, and microtubules 

(m). Microtubules are represented by an array 

of parallel tubular tracks and facilitate movement of 

proteins and organelles within the cell. The ER is a system 

of tubes and sacs, that work with dictyosomes to 

produce and secrete compounds and deliver specific 

proteins and membrane lipids to their proper locations 

within a cell. 

Also, there may be plastids such as chloroplasts (n), leucoplasts, 

and chromoplasts; and non-living substances 

of water-soluble products or reserve substances such 

as oil droplets, protein bodies, and crystals (see 3). 

Nucleus. The nucleus is enclosed by a double membrane 

(o) that has pores (p) in it to allow communication 

with the cytoplasm (f). Within the nucleus are chromosomes, 

which contain DNA needed to create proteins 

within the cell. Chromosomes are only visible during cell 

division (see 6 and 7). Also present in the nucleus are 

one or more nucleoli (q) containing RNA. The rest of the 

nucleus is filled with nucleoplasm (r). The information 

needed to create the entire plant is within the nucleus, 

mitochondria, and chloroplasts of each cell. 

COLOR CODE 

tan: cell wall (a), middle lamella (b), 

dictyosome (l) 

colorless: intercellular space (c), pit field (d), 

plasma membrane (e), vacuolar 

membrane (j) 

purple: smooth ER (g), rough ER (h) 

black: ribosome (i) 

green: chloroplast (n) 

blue: mitochondrion (k) 

orange: mitrotubules (m) 

red: nuclear membrane (o), pore (p) 

gray: nucleolus (q) 

pink: nucleoplasm (r) 

yellow: cytoplasm (f), plasmodesmata (s)

Cell Organelles 

The cytoplasm (cytosol) of a plant cell contains various 

organelles with specific functions. With the use 

of a transmission electron microscope (TEM), which 

shows structures magnified thousands of times, these 

organelles can be viewed individually. The organelles 

represented here are not shown in proportion to one 

another. 

Plastids. Plastids are classified by the primary pigment 

they contain. Young cells have undifferentiated 

plastids (proplastids), which can multiply by simple division. 

They develop into the various kinds of plastids 

characteristic of mature cells. 

Chloroplast. This plastid (a) is where photosynthesis 

takes place. In higher plants it is usually oval-shaped 

and is surrounded by a double membrane (b). Within 

it are sac-like structures (shown cut in half) called thylakoids 

(c). A stack of thylakoids is called a granum (d), 

and this is where green chlorophyll pigments are located. 

Chlorophyll and proteins bound to the thylakoids 

use light energy to make simple sugars from carbon 

dioxide and water (photosynthesis, see 24). 

Extensions from some thylakoid membranes form interconnections 

between grana. The thylakoids also 

contain accessory pigments, carotenoids, and xanthophylls. 

In the stroma (e) of the chloroplast are DNA, 

RNA, oil droplets (f), ribosomes (g), and other materials 

such as starch grains, found in chloroplasts of green 

plant tissues that have been actively photosynthesizing. 

Leucoplast. Such colorless plastids contain storage 

products, which include oils, protein bodies, or starch 

3 

grains. In plant parts with a high starch content, such as 

potato tubers or rice grains, a leucoplast that contains 

starch grains (h) is called an amyloplast (i). 

Chromoplast. These plastids are colored red (k), orange 

(l), or yellow (m), depending on the pigments they 

contain. In the changing colors of ripening fruit such 

as a tomato or a red pepper, the chloroplasts (green) 

differentiate into chromoplasts (orange to red). As fruit 

color changes, so do plastid structure, pigment types, 

and content. 

Mitochondria. These organelles are surrounded by a 

double membrane (n). The inner of these two membranes 

(o) has infoldings, called cristae (p), that protrude 

into the cavity within. Mitochondria are the primary 

sites of enzymes controlling cell respiration (a chemical 

release of energy from sugar or other metabolites). 

They can replicate by simple division and, like chloroplasts, 

they contain DNA. 

Ribosomes. Ribosomes (q) contain ribosomal RNA 

and function in protein synthesis. They are also found in 

cytoplasm, and associated with the endoplasmic reticulum 

(r) in the cytoplasm. 

Dictyosomes (Golgi Bodies). These organelles appear 

as a stack of flattened sacs (s) and associated 

vesicles (t). Dictyosomes produce and secrete cell wall 

polysaccharide precursors and complex carbohydrate 

substances that are secreted out of root cap cells. This 

results in less injury to the growing root as it penetrates 

the soil. 

COLOR CODE 

green: chloroplast (a), thylakoid (c), granum (d) 

white: double membrane (b, n), stroma (e), 

starch grain (h), amyloplast (i) 

yellow: lipid (f), chromoplast (m) 

black: ribosome (g, q) 

blue: inner membrane (o), crista (p) 

red: chromoplast (k) 

orange: chromoplast (l) 

purple: endoplasmic reticulum (r) 

tan: dictyosome sacs (s), vesicles (t)

Cell Pigments 

Chlorophylls. The chlorophylls are oil-soluble. Chlorophyll 

a (greenish-yellow in solution) is the primary 

photosynthetic pigment in green plants for the transfer 

of light energy to a chemical acceptor. Light that is 

absorbed provides the energy for photosynthesis (see 

24). A green leaf absorbs blue light (mostly at 430 

nm) and red light (mostly at 660 nm). It reflects the 

green wavelengths so as to appear green to us. Chlorophyll 

a, alone, is found in blue-greens and in some red 

algae. Accessory pigments in photosynthesis transfer 

light energy to chorophyll a. One of these is chlorophyll 

b (blue-green solution), found in higher plants 

and green algae with chlorophyll a. Chlorophyll c 

is also an accessory pigment found with chlorophyll a 

in brown algae and diatoms. Chlorophyll d, together 

with chlorphyll a, is found in some red algae. 

Carotenoids. These pigments are considered as accessory 

pigments in photosynthesis, when found in 

chloroplasts associated with chlorophyll, and as color 

pigments when found in chromoplasts. Carotenoids, 

like the chlorophylls, are not water-soluble. They absorb 

mainly violet and blue light between 400 and 500 

nm, and they reflect red, orange, yellow, brown, and 

the green color of avocado fruit. They give color to 

carrot roots, tomato fruit, and many yellow flowers. 

Carotenoids of red and yellow are revealed in autumn 

leaves (h, I) after the green chlorophyll pigments begin 

to break down. This occurs when daylengths start to 

shorten and cooler temperatures prevail in temperate 

regions of the world. Carotenes (yellow or orange nonoxygen 

containing pigments) seem to function in the 

prevention of chlorophyll destruction in the presence 

of light and oxygen. β-carotene is the most important 

of the carotines. Xanthophyll pigments are oxygencontaining 

carotenoids. They transfer energy to chlorophyll 

from light. Some of the xanthophylls include lutein, 

zeaxanthin, violxanthin, and fucoxanthin, which is found 

in brown algae. 

Phycobilins. These pigments are water-soluble. As 

accessory pigments they absorb light and transfer excitation 

energy to chlorophyll a. The red pigment, phycoerythrin, 

is found in red algae. The blue pigment, 

4 

phycocyanin, is present in blue-greens and some red 

algae. 

Phytochrome. This pigment plays an important role in 

regulating many processes of plant growth and development. 

Phytochrome is found in two reversible forms. 

One form, Pr, absorbs red light (mostly at 660 nm) and 

reflects a blue-green color. The other form, Pfr, absorbs 

far-red light (mostly at 730 nm) and reflects a light-green 

color. The highest amounts of phytochrome are found 

in meristermatic tissues (see 9). 

Flavinoids. These water-soluble pigments accumulate 

in cell vacuoles. They absorb ultraviolet wavelengths 

of light. Anthocyanins are phenolic pigments 

that are found in most fruits and in many flowers. These 

red-, purple-, and blue-reflecting pigments are seen 

in the red color of apple (Malus) fruit and geranium 

(Pelargonium) flowers; the blue of cornflowers (Centaurea) 

and larkspur (Delphinium); and the red and purple 

of Fuchsia (l, m) flowers. The function of these pigments 

can only be hypothesized, but study of plants having 

these pigments is useful in determining evolutionary 

relationships. Flavins often appear to us as yellow or 

ivory-colored flowers. Some flavins, such a riboflavin 

(vitamin B2), act as co-factors in enzyme reactions and 

some are thought to be receptor pigments in the bending 

of plants toward light (phototropic responses; see 

20). 

Betalains. These are water-soluble, nitrogen-containing 

reddish pigments that are found in only 9 families 

of the flowering plant subclass, Carophyllidae (see 75). 

These pigments are water-soluble and found in the vacuoles 

of cells. Betacyanin appears as blue-violet to red 

and is found in beet (Beta) roots (n) and red cactus flowers. 

Betaxanthin pigments reflect yellow, orange, and 

orange-red. 

COLOR CODE 

purple: column a, petal anthocyanin (l) 

blue: column b 

green: column c, leaf chlorophylls (g), 

ovary (j), peduncle (k) 

yellow: column d, leaf carotenoids (i) 

orange: column e 

red: column f, leaf carotenoids (h), sepal 

anthocyanin (m) 

blue-purple-red: root betacyanin (n)

Cell—Water Movement 

More than 90% of most plant tissues is composed of 

water. Water is needed for most life processes to take 

place. The movement of water (a) from cell vacuole (b) 

to another cell’s vacuole (c) within the plant is by diffusion 

through the cell’s semipermeable plasma membrane 

(d), which encloses the cytoplasm (e). The flow is 

from a region of high concentration of water to a region 

of low concentration of water, a process that is called 

osmosis. The more substances (solutes) dissolved in 

the water, the lower the concentration (water potential) 

of water. For example, in a leaf cell that is producing 

sugar (a solute, f) from photosynthesis, water passes 

into the cell. An osmotic equilibrium is reached when 

water no longer enters the cell. 

Turgor Pressure 

As water (a) passes into a cell, it expands the plasma 

membrane (d), exerting pressure against the cell wall 

(g). This is called turgor pressure. In fully inflated cells, 

turgor pressure is one of the key “driving forces” in plant 

growth. In cells of developing fruits, turgor pressure is 

very important for fruit enlargement, and indicates the 

necessity of keeping plants well watered during this period. 

Turgor pressure maintains the size and shape of 

plant parts such as leaves and flowers. 

5 

Plasmolysis 

Water (a) is lost from a cell when there is a lower water 

concentration in adjacent cells that have more solutes 

present. Turgor pressure within the cell then decreases. 

When there is no turgor pressure, the plasma membrane 

(d) shrinks from the cell wall (g), leaving through 

the cell wall. This process is termed plasmolysis and is 

reversible when water is returned to the cytoplasm and 

vacuole through osmosis. Plasmolysis of cells results in 

wilting of plant shoots and is the opposite of fully turgid 

cells, where plants are fully “inflated” or crisp, like fresh 

celery. 

“Wilting” 

When excessive cell water (a) is lost through evaporation 

to surrounding dry air, “wilting” occurs. In this condition 

cell turgor pressure is lost, the plasma membrane 

(d) shrinks from the cell wall, and cell wall (g) contracts 

because there is no external solution to fill in between. 

This condition can result in plants that are “permanently 

wilted” if the wilting persists over a period of 10 to 12 

days. If wilted plants are watered before they reach the 

permanent wilting condition, they regain turgor in several 

hours time. 

COLOR CODE 

dark blue: water (a) 

colorless: vacuole membrane (b, c), plasma 

membrane (d) 

yellow: cytoplasm (e) 

light blue: sugar solution (f) 

tan: cell wall (g) 

red: nucleus (h) 

gray: external solution (i)

Cell Chromosomes 

Chromosomes (a) are the darkly stained microscopic 

bodies in the nucleus which contain genetic information 

(genes) that determine inheritance characteristics 

of an organism. A chromosome basically consists of 

a core of DNA (deoxyribonucleic acid) surrounded by 

a jacket of basic protein called histone. Bacteria and 

blue-greens have no nuclei or chromosomes, but instead, 

have a DNA-bearing structure called a nucleoid 

(see 43). Some of their DNA may be in circular forms 

called plasmids (b). 

Chromosome Structure. Chromosomes are composed 

of chromatin, which can be seen microscopically 

with the use of stains such as the Feulgen reagent or 

acetocarmine. Chromosomes are best observed during 

mitotic or meiotic division, when the chromatin is 

condensed and chromosomes visible (see 7, 30). Chromosomes 

have a simple external structure. A chromosome 

(a) has a small body called a centromere (c) 

with “arms” (d) on either side. The part of the centrome 

where spindle fibers are attached is called a kinetochore. 

Small segments, almost circular, that occur near 

the ends of a chromosome are called satellites (e). 

During mitosis and meiosis, the chromosome replicates 

into two strands called chromatids (f) attached together 

at the centromere. Chiasma (crossing-over) 

is when chromatids (f) overlap, break, and exchange 

segments with other chromatids (g) during meiosis. It 

may involve 2, 3 or all 4 chromatids. This can give rise 

to genetic variability or mutations. 

Chromosome Number. Chromosome number is characteristic 

for the majority of vegetative (somatic) cells of 

an organism. This is called the 2n or diploid number. 

Organisms whose somatic cells contain multiple sets of 

chromosomes are called polyploids. These occur as a 

result of hybridization between sexually compatible parents 

with different chromosome numbers. Polyploidy is 

widely evident in plants, but is rare in animals. 

6 

COLOR CODE 

purple: chromosomes (a), centromere (c), 

“arms” (d), satellite (e), chromatids (f) 

blue: plasmid outline (b) 

red: chromatids (g) 

green: chromosomes (h) 

black: chromosomes (i)

Cell—Mitosis 

Mitosis is a process of nuclear division in which chromosomes 

divide lengthwise, separate, and form 2 identical 

nuclei. Mitosis is usually accompanied by cell division, 

which involves the formation of a new cell wall 

between the 2 identical nuclei. In plants, good sites to 

observe mitosis are in root tips, shoot apices, and newly 

developing leaves. This is done by making thin sections 

of the tissues, mounting them on slides, staining them 

with acetocarmine or Feulgen stains, then observing 

the sections with the high power or oil immersion lens 

of an optical (light) microscope. 

The Cell Cycle 

The period when the nucleus is between divisions is 

called interphase. During interphase is a period of 

replication of cytoplasmic organelles, followed by a 

period when chromosomes (a) are duplicated, then 

a period when spindle fibers (bundles of microtubules) 

are made. Phases of mitosis are prophase, 

metaphase, anaphase, and telophase. Interphase 

and the 4 phases of mitosis constitute the cell cycle. 

Phases of Mitosis 

Prophase. At the first stage of mitosis, the chromosomes 

(a) become visible as long threads. For clarification 

only 3 chromosomes are shown. On each strand 

7 

is a small body called a centromere (f). Then the chromosomes 

start to shorten and thicken and divide into 

2 helical coiled strands called chromatids (g). DNA is 

replicated half to each chromatid. 

Metaphase. In stained cells on microscope slides, the 

nuclear membrane and nucleolus (b) can no longer be 

seen during metaphase in vascular plants. Metaphase 

is marked by the appearance of the spindle (h). It is at 

this time that the chromosomes migrate to the spindle 

and the centromeres (f) align in a flat equatorial plane. 

The pairs of chromatids (g) are held together at the 

centromeres (f). 

Anaphase. Anaphase is initiated with division and separation 

of the centromere, providing each chromatid 

with centromere (f). This phase ends with the chromatids, 

which are now called chromosomes, moving 

to opposite poles (i) of the spindle (h). 

Telophase. This phase begins with the chromosomes 

(a) completing their movement to the poles. It ends with 

the chromosomes once more becoming diffuse, as in 

interphase. A new nuclear membrane (c) forms around 

each group of chromosomes (a) and nucleoli (b) reappear. 

During interphase, a new cell wall (e) forms between 

the nuclei. 

COLOR CODE 

purple: chromosomes (a), centromere (f), 

chromatid (g) 

gray: nucleolus (b) 

red: nuclear membrane (c) 

yellow: cytoplasm (d) 

tan: cell wall (e) 

orange: spindle (h)

Cell Types 

Parenchyma Cells 

Parenchyma cells (a) make up the major portion of the 

primary plant body. They are usually thin-walled and 

vary in shape from spherical with many flat surfaces, 

to elongated, lobed, or folded. As living cells that are 

unspecialized initially, they later differentiate to more 

specialized cells. Parenchyma cells are found in photosynthetic 

tissue of green leaves and green stems, in 

epidermis, below the epidermis in cortex (b), in pith, and 

in the vascular system. 

As food storage cells, they occur in specialized organs 

such as bulbs and tubers, in seeds (as endosperm), and 

in seed leaves (cotyledons). Specialized parenchyma 

tissue (also called aerenchyma) with intercellular air 

spaces aids water plants in floating. Parenchyma cells 

may appear as secretory forms such as glandular and 

stinging hairs, nectaries, and salt glands. 

Collenchyma Cells 

Collenchyma cells (c) provide elastic support to stems 

and leaves due to variously thickened primary walls (d) 

containing cellulose, hemicellulose, pectin, and water. 

These closely arranged, living cells are short or elongated 

in shape. They are usually found near the surface 

in the cortex around vascular bundles (e) of leaf petioles 

and stems. 

Sclerenchyma Cells 

Sclerenchyma tissue cells function in mechanical support 

due to thick lignified secondary walls (f), which contain 

large amounts of cellulose and lignin. At maturity, 

some sclerenchyma cells no longer have living protoplasts. 

Fibers and sclerids are types of sclerenchyma 

cells. 

Fibers (g) are elongated cells with pitted cell walls (h). 

They are found in water-conducting tissue, xylem (i) and 

food-conducting tissue, phloem (j), along leaf veins and 

margins, and surrounding vascular bundles in stems. 

Examples of commercial fibers are hemp, flax, jute, rattan, 

and cotton, used in making rope, mats and baskets. 

Sclereids are dense (lignified), short cells which may 

look like stones, rods, bones, stars, or branched structures. 

Familiar forms, with dense cell layer of sclereids 

occur in nut shells, fruit pits, and the seed coats in 

8 

legume tree pods (Fabaceae, see 100). Pear (k) and 

quince fruits contain “stone cells” (l), that is, nests of 

sclereids in the fleshy mesocarp (m) tissue (see 39). 

Vascular Cells 

Cells of the xylem tissue, tracheids (n), are elongated, 

have bordered wall pits (o) for water conduction, and 

are aligned side by side. Also, water- and mineralconducting 

cells of the xylem, namely, the vessel 

elements (p), have bordered pits (q) in their cell walls. 

The vessel elements are aligned end-to-end to form 

long tubes. The xylem sap passes vertically through 

the vessel elements via end perforations that may be 

parallel slits (r) or a single large opening (s). Conifers 

and primitive woody flowering have only tracheids for 

water conduction. 

Sieve cells are enucleate (minus a nucleus), found in 

the phloem of conifers and primitive vascular plants 

such as ferns. The sieve cells are elongated and thinwalled. 

Sieve-tube elements (t) are enucleate and 

found in more advanced flowering plants. Both sieve 

cells and sieve-tube elements form long end-to-end 

columns called sieve tubes. Sieve plates (u), consisting 

of primary pit fields, occur in the end walls of sieve 

tube elements. In sieve cells, the walls, over their surfaces, 

contain localized sieve areas containing many 

pores that allow for cell-to-cell solute transport. Cell-tocell 

connecting strands of cytoplasm pass through the 

sieve plates. 

Companion cells (v), a specialized type of parenchyma, 

may be present in varying numbers in association 

with sieve tube elements. 

COLOR CODE 

green: parenchyma cells (a), collenchyma cells 

(c) 

light green: parenchyma cortex (b) 

white: vascular bundles (e), xylem (i), phloem 

(j), mesocarp (m) 

tan: fibers (f, g, h) 

yellow: pear epidermis (k), sclereids (l) 

blue: tracheid (n, o), vessel elements (p, q, r, 

s) 

orange: sieve-tube elements (t), sieve plate (u), 

companion cells (v)

Tissue Systems of the Plant Body 

Cells in plants are arranged in tissues such as epidermis, 

cortex, and pith. Several tissues also make up a 

tissue system such as the vascular system. 

Meristems 

Throughout the life of a plant, new cells are continuously 

being formed at sites called meristems. Meristems 

consist of undifferentiated cells that are found at 

shoot tips, at root tips, in the vascular cambium, and in 

the cork cambium. Meristems produce cells that differentiate 

into specialized tissues of three systems: dermal, 

ground, and vascular. Only primary growth (left column), 

resulting from the activity of the shoot and root 

apical meristems, is found in some herbaceous dicots, 

most monocots, and lower vascular plants. Conifers and 

woody dicot shrubs and trees exhibit secondary growth 

(right column). 

Shoot Tissue Systems 

The shoot is the portion of the plant above the roots and 

is composed of stems, leaves, flowers and fruits. The 

stem apical meristem (a) forms leaf primordia (b) on its 

flanks and young stem tissues below during the vegetative 

phase, and in flowering plants, flower primordia 

during the reproductive phase. 

Dermal Tissue System. The outer layer of the apical 

meristem gives rise to the epidermis (c) of the primary 

plant body. In the stems of plants with secondary 

growth, the epidermis is replaced by periderm (d), commonly 

called the “outer bark.” Periderm consists of the 

meristematic cork cambium producing cork (phellem) 

outward and the pelloderm inward (see 15). 

Ground Tissue System. The cells and tissues of the 

ground tissue system are derived from the apical meristem. 

In the diagram, ground tissue is manifest as cortex 

(e), located between epidermis and vascular bundles, 

and pith (f) in the center of the stem. 

Vascular Tissue System. Also derived from the apical 

meristem, the procambium (g) initiates the vascular system 

with cells that differentiate inside into primary xylem 

(h), the water- and nutrient-conducting tissue, and outside 

into primary phloem (i), the food-conducting tissue. 

In plants with secondary growth, a persistent cambium, 

the vascular cambium (j), makes possible added layers 

9 

of secondary xylem (k) and phloem (l), resulting in an 

increase in stem diameter. 

Root Tissue Systems 

The root apical meristem (m) produces new root cap 

(n) cells ahead (below) of the root apex, as well as cells 

of the protoderm (young epidermis), ground meristem, 

and procambium back of the root apex. 

Dermal Tissue System. With primary growth, roots 

are covered with epidermis (o). With secondary growth, 

the epidermis and root hairs (derived from epidermal 

cells) are sloughed off because of formation of periderm 

(p) on the outside. 

Ground Tissue System. Cortex (q) lies between the 

epidermis and vascular system in portions of roots 

undergoing primary growth. The innermost layer of cortex, 

the endodermis (r), bounds the pericycle tissue 

(s), which surrounds the primary vascular system. In 

portions of roots undergoing secondary growth, the cortex, 

like the epidermis, is shed as the periderm develops 

cork cells. 

Vascular Tissue System. In the root, unlike the stem, 

the primary vascular system is in a central cylinder (t) 

with xylem and phloem arranged in an alternate radial 

manner. Primary xylem “arms” (u) radiate out from the 

center with alternate poles of primary phloem (v) in the 

outer portion of the cylinder. Between them is procambium 

(w). In older portions of roots, where secondary 

growth is evident, the vascular cambium (x) produces 

successive layers of secondary xylem (y) and phloem 

(z). 

COLOR CODE 

red dot: apical meristem (a, m) 

red line: procambium (g, w), vascular 

cambium (j, x) 

colorless: epidermis (c, o), pith (f), root cap (n), 

endodermis (r), central cylinder (t) 

green: young leaf (b), shoot cortex (e) 

blue: primary xylem (h, u) 

light blue: secondary xylem (k, y) 

orange: primary phloem (i, v) 

light orange: secondary phloem (l, z) 

tan: root cortex (q), periderm (d, p) 

yellow: pericycle (s)

Tissue—Epidermis 

Usually a single layer of cells (a) makes up the epidermis 

that covers roots, stems, leaves, and fruits. At 

the outer surface of the epidermal cells is a continuous 

layer (cuticle, b) made up of fatty material (cutin). 

It is sometimes overlaid with a protective, waterproof 

coating of wax. Oil, resin, and salt crystals may also be 

deposited on the surface. Functions of the epidermis 

include mechanical support, protection from desiccation 

(drought) and against attack by virulent pathogenic 

organisms and insects, gas exchange, restriction of water 

loss by evaporation (transpiration) through stomates 

and water and mineral storage. 

In a surface view, the epidermal cells appear hexagonal, 

elongated, or wavy-margined (c) like jigsaw puzzle 

pieces. Shape varies with the plant part being examined, 

such as root, stem, leaf (d), flower parts (e), or 

fruit. Some plants such as those in the grass family 

(Poaceae), have parallel rows of elongated cells (f) alternating 

with short specialized silica (g) and cork (h) 

cells, stomata (i) and trichomes. Pits (j) are present in 

the elongated cells. 

Guard Cells. In stomata, pairs of guard cells (k), specialized 

epidermal cells, control air exchange (CO2 and 

O2) and water loss from plants by changing the size of 

the pore (stoma, l) that separates their inner walls. A 

pair of guard cells can expand or contract as a result 

of changes in turgor pressure. Usually, as guard cells 

develop high turgor pressure, stomata open, and with 

reduced turgor pressure, they close. The stomatal pore 

(l) allows gas exchange to occur between outside air 

(m) and inner plant (n) tissues. Other cells, called subsidiary 

cells (o), may be associated with guard cells. 

Trichomes (Hairs). The epidermis may have various 

extensions of one- or many-celled hairs (trichomes, r) 

some of which may be glandular. Glandular excretions 

include terpenes (essential oils, carotenoids, saponins, 

or rubber), tannins, or crystals (such as salt). 

10 

Fragrance in flowers is provided when essential oils in 

the petals vaporize. Non-glandular hairs may be found 

on any shoot surface as well as on seeds such as cotton 

(see 90) and willow (see 95). 

Menthol in mints is produced in hairs on the leaves. It 

is the primary flavoring constituent of peppermint too. 

Many members of the mint family (Lamiaceae, see 113) 

and aster family (Asteraceae, see 119) produce terpenes 

in hairs in leaves and stems that repel herbivores 

like deer. The glandular hairs on bracts of the female 

flowers of hops produce humulone that is responsible 

for the bitter principle in beer. 

The leaves and stems of hemp or marijuana (Cannabis 

sativa) are covered with hairs that contain over 20 different 

cannabinoids responsible for hallucinogenic properties 

of this plant. These constituents also help in treating 

patients with glaucoma and allaying the adverse side 

effects of chemotherapy in treating cancer. 

Nectar Glands. Nectar glands, found in various flower 

structures and on stems and leaves, produce a sugar 

solution. Some flowers have specialized scent glands 

(osmophors) in the form of flaps, hairs, or brushes. 

Glands on the surface of carnivorous plants produce 

nectar (s) or enzymatic digestive fluids (t). 

Root Hairs. Root epidermal cells (u) function in the 

uptake of water and dissolved minerals. Most plant 

roots produce extensions from the epidermal cells of 

trichomes called root hairs (v). They occur above the 

elongation zone of the root. At maturity, root hairs collapse 

as the epidermal cells are sloughed off. Alternatively, 

they may remain intact due to lignification of their 

cell walls. But even these root hair cells may disappear 

as bark forms on the root in more mature regions. 

COLOR CODE 

colorless: cells (a, c, d, e, f, k, o, t, u), pits (j) 

yellow: cuticle (b) 

gray: silica cells (g) 

tan: cork cell (h) 

green: chloroplast (p) 

red: nucleus (q) 

optional: trichomes (r, s, v)

Tissue—Primary Vascular System 

In the primary plant body, the vascular system is 

made up of vascular bundles composed of conducting 

elements, interspersed with fibers for support and 

parenchyma cells for food storage. Procambial cells (a) 

give rise to primary xylem toward the inside and primary 

phloem toward the outside of the plant. In most 

monocots, after differentiation of vascular elements, no 

procambium remains. 

Xylem: Water-conducting Tissue 

Several types of cells (living and non-living) make up 

xylem tissue: tracheary elements (b), composed of tracheids 

(c) and vessel elements (d), which conduct water 

and nutrients; fibers (e), which provide support; and 

living parenchyma cells (f), which store food. Sclereids 

may also be present. In monocots, vessel elements, 

whose walls have been stretched and broken by elongation, 

result in spaces (lacunae, g) in the xylem. 

Bordered Pits. The primary walls of tracheids and vessel 

elements have depressions called primary pit fields. 

When secondary walls (h) are formed, the bordered 

holes (pit apertures, i) consist of a pit chamber (j) and a 

pit membrane (k). Of two adjacent cells, the pits of each 

are at the same level forming pit-pairs. Composed of the 

primary wall of each of the two adjacent cells, the pit 

membrane is permeable and allows passage of water 

and mineral nutrients from cell to cell. 

Phloem: Food-conducting Tissue 

Phloem tissue is composed of sieve elements of sieve 

cells or sieve tube elements (o) for food conduction, 

fibers (m), and parenchyma cells (n). Companion 

cells (s) are associated with sieve tube elements. 

Latex-producing cells (laticifers) and sclereids may be 

present. 

(Dicot vascular bundle adapted with permission: Esau, 

K., Plant Anatomy, 1967, John Wiley & Sons.) 

11 

COLOR CODE 

red: procambial cells (a) 

colorless: parenchyma cells (f, n), lacuna (g), 

pit membrane (k), secondary wall (h) 

blue: tracheary elements (b, c, d) 

tan: fibers (e, m) 

orange: sieve tube elements (l), companion 

cells (o)

Root Types and Modifications 

The root is the underground organ of the plant. Its primary 

functions include uptake of water and minerals 

and anchorage of the above-ground (aerial) portions of 

the plant. 

Root Types 

In conifers and dicots, a primary root (a), called a radicle 

in the seed embryo, develops lateral branching roots 

(b). As this system develops further, the individual roots 

may show secondary growth due to cambial activity. 

The cambium is a meristem that produces secondary 

xylem, and secondary phloem (see 9). 

In many monocots, the first-formed roots of the 

seedling, called seminal roots, eventually die. They 

are replaced by adventitious roots (d), which emerge 

from the stem. Dicots may also have accessory adventitious 

roots, for example, the aerial roots on vines such 

as ivy (see 16). 

Root Modifications 

Storage Roots. Plants may develop specialized, thickened 

roots, as those found on carrot (Daucus, f), beet 

(Beta), sweet potato (Ipomea batatas, see 112), manroot 

(Ipomea pandurata), tuberous begonia (Begonia), 

and dahlia (Dahlia). These roots are an adaptation for 

food storage and are seen in many biennials and perennials. 

A biennial plant is one that produces leaves the 

first year and flowers and fruit the second year, then 

dies. A perennial plant lives for more than two years. 

Prop Roots. Some plants develop supporting roots as 

found in corn (Zea, h) and mangrove (Rhizophora). 

Such roots are especially effective in anchoring the 

shoot system in the soil, preventing them from capsizing 

in strong winds, heavy rains, and impact from predators 

and human activities. 

12 

Contractile Roots. Contraction, or shortening of some 

roots, helps pull down and anchor the plant more firmly 

in the soil. Contractile roots (i) are common in herbaceous 

dicots and monocots, and occur in taproots, adventitious 

roots, and lateral roots, and on roots of underground 

storage stems such as bulbs and corms. (An 

herbaceous plant or herb is nonwoody and can die to 

the ground in freezing climates.) 

Symbiotic Relationships in Roots 

Nodules Involved in Nitrogen Fixation. Some plants 

are stimulated by certain genera of bacteria to develop 

extra tissues in the roots in the form of nodules (l), 

where nitrogen (N2) in the air is “fixed,” that is, converted 

to other forms, mainly ammonia (NH3), which 

can then be converted to organic forms such as amino 

acids. The bacteria and plant exchange nutrients and 

metabolites in a mutually beneficial relationship. Examples 

are found in alfalfa (Medicago), clover (Trifolium), 

garden pea (Pisum sativum), and garden bean (Phaseolus 

vulgaris). 

Mycorrhizae. These are mutually beneficial associations 

between fungi (n) and plant roots (o). For the plant, 

the fungi increase the uptake of minerals, particularly 

phosphorus, and also water. For the mycorrhizal fungus, 

the plant root cells provide sugars, amino acids, 

vitamins, and water. Mycorrhizae are classified according 

to whether the fungal strands (hyphae) invade (endomycorrhizae) 

or surround (ectomycorrhizae) the root 

cortical cells. A third class is where fungi both invade 

and surround (ectendomycorrhizae) root cortical cells. 

Most plants have mycorrhizal associations, which help 

them compete with other plants. Mycorrhizae develop 

best in nutrient-poor soils. 

COLOR CODE 

tan: dicot root system (a, b), scale leaves (j), 

stem axis (k), nodules (l) 

green: leaves (c, e, g), prop roots (h) 

white: monocot root system (d), roots (i, m, o), 

roots swollen with mycorrhizal fungal 

strands (n) 

orange: storage tap root (f)

Root Tissues 

Basic Differentiation Regions of the Root 

Apical Meristem. The root apical meristem (a) is located 

at root tips. It produces new root cap (b) cells 

below, and above, it produces cells that contribute to 

protoderm (c), ground meristem of the cortex (d), and 

procambium (e), the three primary meristems that initiate 

tissues. 

Root Cap. The function of the root cap (b) is to protect 

the apical meristem and to aid the developing root as it 

penetrates the soil as the root elongates. It is composed 

of parenchyma cells whose walls, along the surfaces of 

the root cap, are mucilaginous to provide easier passage 

through soil particles. As cells (f) are sloughed 

off, more cells are produced by the apical meristem. 

Elongation Region. Back of the apical meristem is the 

region (g) where most elongation of the root takes place. 

Mature Root. In primary growth, the epidermal cell 

walls of the mature root (j) become cutinized or suberized 

with wax-like substances. With secondary growth, 

the cork cambium replaces epidermis (k) and cortex 

with root bark tissues, cork and phelloderm. 

Non-vascular Tissue Systems 

Epidermis. The epidermis is the outermost tissue of 

the root. It is usually a single layer. In the root elongation 

zone are root hairs (h), lateral protrusions of epidermal 

cells (i), which are active in water and mineral nutrient 

uptake. 

Cortex. Basically, cortex tissue is made up of 

parenchyma cells. In conifers and dicots with secondary 

growth, the cortex (d) is shed. Monocots, without secondary 

growth, retain their cortex and many develop 

sclerenchyma tissue. Food, mostly as starch, is stored 

in the cortical cells in amyloplasts (see 3). Proplastids 

may develop into chloroplasts in cortical cells if the root 

is exposed to light. 

Endodermis. The innermost layer of cortex (d) that encircles 

the vascular tissue is called the endodermis (l). 

13 

Along the radial and transverse walls of endodermal 

cells is a suberin-rich fatty layer called the casparian 

strip (m). It blocks absorbed soil water from passing 

between the cells to the xylem; thus, water and mineral 

nutrients must pass through the selectively permeable 

membranes of endodermis cells instead, an effective 

filtering system (see 17). 

Vascular Tissue System 

Pericycle. The central cylinder (n) of vascular tissue 

is surrounded by thin-walled parenchyma tissue called 

pericycle (o). The pericycle is the site where vascular 

cambium and lateral roots originate. As a lateral root (p) 

penetrates through the cortex, its apical meristem and 

its derivative tissue systems become organized. Adventitious 

roots, which develop from stems, are initiated in 

parenchyma near differentiating vascular tissue. 

Xylem. If no xylem is formed in the center of the root, 

parenchyma tissue develops there. Primary xylem arms 

(q) radiate from the center and vary in number. The 

dicot types include diarch (2 arms), triarch (3 arms), or 

tetrarch (4 arms, q), and the monocot type is polyarch 

(many arms). 

Phloem. Procambium cells (e), between the radiating 

arms of primary xylem, produce primary phloem (r) outward 

and xylem tissue inward. In secondary growth, the 

vascular cambium (s), which originates from the pericycle, 

extends completely around the tips of the xylem 

arms and inside the primary phloem poles. It produces 

secondary xylem (t) inward and secondary phloem (u) 

outward. (For a further stage in secondary growth, see 

9, root cross-section.) (Lateral root adapted with permission: 

Esau, K., Plant Anatomy, 1967, John Wiley & 

Sons.) 

COLOR CODE 

red: apical meristem (a), procambium (e), 

vascular cambium (s) 

colorless: root cap (b), protoderm (c), root regions 

(g, h, i, j), cortex (d), cells (f), epidermis 

(k), lateral root (p) 

tan: endodermis (l), casparian strip (m) 

yellow: pericycle (o) 

blue: central cylinder (n), primary xylem (q) 

light blue: secondary xylem (t) 

orange: phloem (r) 

light orange: secondary phloem (u)

Stem Structure 

Functions of the stem include: photosynthesis; longdistance 

transport of hormones and organic metabolites 

in the phloem; transport of water and mineral nutrients 

in the xylem; support of the shoot system; sites for 

responses of shoot to gravity (gravitropism) and unilateral 

light (phototropism); food storage; and sites of 

initiation of adventitious roots, new leaves and inflorescences 

(flowers). 

Parts of a Stem 

Shoot Tip. The stem shoot apex produces leaf primordia 

(a) that develop into leaves (b). 

Node. The site where a leaf or leaves, as well as axillary 

buds, arise on the stem is termed a node (c). 

Internode. The elongated portion of a stem between 

two nodes is called an internode (d). 

Bud. A terminal bud (e), which develops at the apical 

end of the stem, encloses a meristematic stem axis (f) 

with its apical meristem (g). Axillary buds (h) are lateral 

buds that form at the leaf-stem axils (nodes) and may 

develop into lateral vegetative shoots or flowers. 

Bud Scales. Small, modified leaves or stipules that 

cover and protect the bud are called bud scales (i). 

Some buds lack scale coverings and are called naked 

buds. 

Bud Scale Scar. Perennial woody stems exhibit scars 

(j) at the sites where terminal bud scales were shed 

during previous years (k, l). 

Leaf Scar. A scar remains on the stem where a leaf 

stalk (petiole) was attached. Leaf scars (m) and buds 

are species-specific, and therefore, are useful for winter 

plant identification. 

Bundle Scar (Leaf Trace). The vascular bundles (j) from 

a shed leaf appear as dots within a leaf scar. 

Lenticel. Openings for gas and water exchange in the 

stem surface, called lenticels (o), are found on some 

plants with secondary growth. Lenticels are very prominent, 

for example on cherry (Prunus) tree bark. 

14 

COLOR CODE 

red: apical meristem (g), maple bud scales 

(i), procambium (p) 

green: leaf primordia (a), leaf (b), node (c), 

stem internode (d), bean terminal bud 

(e), bean axillary bud (h) 

white: stem axis (f) 

tan: lilac bud scales (i), leaf scar (m) 

dark brown: bud scale scars (j), bundle scars (n), 

lenticels (o) 

gray-pink: stem growth, last year (k) 

gray: stem growth, 2 years ago (l)

Stem Tissues 

Meristems 

In the primary state of stem growth, the apical meristem 

at the shoot apex produces cells that differentiate 

into the three primary meristems. They are the ground 

meristem, which gives rise to pith, cortex of the stem 

and the mesophyll of leaves, the procambium, which 

produces primary xylem and phloem of the vascular 

system, and protoderm, which produces the epidermal 

system. In plants with secondary growth, the protoderm 

is replaced by the vascular cambium. An intercalary 

meristem (a) is temporary, located between tissues 

that already have differentiated. Examples include internodes 

of grasses and Equisetum; leaves of conifers 

and Welwitschia (see 74); fruiting stalks of peanut; and 

stipes of kelps (see 60). 

Ground Tissue System 

Dicot and Conifer Stems The ground tissue between 

vascular tissue (d) and epidermis (e) is cortex (f). It consists 

of parenchyma tissue with intercellular spaces, but 

may include sclerenchyma and collenchyma tissues. 

If the vascular tissue forms a ring between the cortex 

and the center of the stem, in the center is pith (g). In 

conifers, the cortex (f) may have resin ducts (h). 

Monocot Stem. With usually dispersed vascular bundles 

(i) in the ground tissue, the parenchyma (j) is not 

differentiated into pith or cortex. 

Vascular Tissue System 

Dicot and Conifer Stems. Vascular bundles (d) are 

arranged in a ring around the stem. In primary growth, 

all cells of the procambium differentiate into primary 

vascular tissue (k, l). In plants with secondary growth, 

some of the meristematic cells remain and usually form 

a contiguous ring of vascular cambium (m), which begins 

to produce secondary phloem (n) outside, and secondary 

xylem (o) inside. The yearly additions of secondary 

xylem are commonly called “growth rings.” The 

ages of trees are determined by the number of growth 

rings in the trunk near the base of the tree trunk. Rings 

can be counted visually or by use of an increment borer. 

The cambium forms two systems of vascular tissue, 

one vertically up the axis, and the other horizontally 

across the axis (called a ray system). Inward from the 

cambium, xylem rays (p) are produced, and outwardly 

phloem rays (q) are produced. Associated with the rays 

15 

are gum ducts in dicots, which contain resins, oil, gums, 

and mucilages. Comparable to gum ducts, some 

conifers have resin ducts. Secondary xylem tissue, 

“wood,” may be composed of sapwood (r) and heartwood 

(s). Sapwood consists of live xylem components, 

active in the transport of water and mineral nutrients. 

The inner heartwood is composed of inactive xylem 

that stores secondary metabolites. Organic compounds 

such as oils, gums, resins, and tannins fill the cells that 

prevent wood rot caused by fungi and other organisms. 

Monocot Stem. Monocots have no vascular or cork 

cambia and, therefore, no secondary growth. They exist 

in a primary state of growth (herbaceous plants). In 

large plant bodies such as palms, a thickening of the 

trunk occurs by multiple divisions of parenchyma cells 

of the procambium. In some members of the lily family 

(Liliaceae) such as Yucca and Dracaena, divisions outside 

the vascular bundles account for thickening of the 

stem axis. 

Secondary Dermal Tissue 

In woody dicots and conifers, the epidermis is replaced 

by periderm (t), “outer bark.” The periderm is composed 

of cork cambium (phellogen, u), cork (phellum, 

v) and phelloderm (w). The cork cambium (u) produces 

phellem (v) toward the outside and phelloderm (w) toward 

the inside of the periderm. Cork cells at maturity 

are dead, and most are filled with suberin. The cork 

covering of stem surfaces functions for protection. It is 

compressible and water- and oil-resistant, and protects 

against insect and fungal attacks, cold, and, in some 

trees (e.g. redwood and sequoia), fire. Openings in the 

cork tissue, lenticels (x), serve, the same function as 

stomata in gas exchange. Secondary phloem (n) and 

periderm (t) together are commonly called “bark.” 

COLOR CODE 

red: intercalary meristem (a), vascular 

cambium (m), cork cambium (u) 

green: ridge (b), grooves (c), cortex (f), 

parenchyma (j) 

colorless: epidermis (e) 

yellow: resin ducts (h) 

orange: primary phloem (k) 

blue: primary xylem (l) 

light orange: secondary phloem(n), phloem rays (q) 

light blue: secondary xylem (o,r,s) xylem rays (p) 

tan: pith (g), periderm (t), cork (v, x), 

phelloderm (w)

Stem Modifications 

Stems may be of various forms to serve different functions, 

such as for food or water storage, for subterranean 

or aerial anchoring devices, as a means of asexual 

reproduction, or for climbing. 

Bulb. A bulb is a short, underground, food-storage 

stem axis with extremely reduced internodes and surrounding 

fleshy scale leaves (a). An onion is the example 

here. 

Corm. A solid, bulb-like, underground stem without 

fleshy scales forms a corm. It has greatly shortened internodes. 

Examples are the food-storage, reproductive 

corms of Gladiolus and Crocus (shown). 

Pseudobulb. Many orchids grow on branches or 

trunks of other plants (epiphytes). These plants develop 

a fleshy stem internode with water storage 

parenchyma. Other orchids, in contrast, are terrestrial 

(grow in the soil.) 

Rhizome. Found near or below the soil surface, a rhizome 

is an underground stem that produces scale-like 

leaves and adventitious roots at the nodes. Rhizomes 

are in Iris (see 129), Equisetum (see 20, 66), and Irish 

potato. A potato rhizome with a developing, edible tuber 

is shown. 

Spur Shoot. Some trees have short, woody stems 

with shortened internodes, such as apple (see 99) and 

Ginkgo (see 72). In apple, the spur shoots produce flowers 

and fruits. In Ginkgo, they produce pollen-producing 

male strobili on male trees or fruits from female strobili 

on female trees (dioecious condition, see 72). 

Stolon. A lateral stem, “runner” (k), from the base of 

a plant develops long internodes, and where the apex 

touches the soil, a new plant with shoots and adventitious 

roots forms at a node. Strawberry (see 20) and 

strawberry begonia (shown) form stolons. 

16 

Succulent Stem. Fleshy water storage stems of 

parenchyma are found in the spurge (see 103) and cactus 

(see 85) families. A fleshy cactus stem is shown. 

Other families containing representative genera with 

fleshy stems are found in the aster family (see 119) 

and geranium family (see 108). 

Tuber. Tubers are swollen, underground food storage 

stems arising at the tips of rhizomes. They bear buds, 

“eyes,” at the nodes on the potato tuber. These “eyes” 

develop into potato sprouts (shoots) when the potato 

starts to grow. 

Vine. Vines are stems with long internodes and may 

have one of various types of climbing devices such 

as tendrils opposite leaves at a node as in grape (see 

104), modified stipule tendrils (w) as in green briar, disctipped 

tendrils (t) as in Virginia creeper, adventitious 

roots as in philodendron and ivy (q), twining leaf tips as 

in gloriosa lily, and twining leaf petioles as in clematis, 

or the entire vine may twine as in wood rose (Ipomoea 

tuberosa). 

Of interest...A bizarre wide flattening of the stem in 

some plants is called fasciation (not shown), caused 

by viruses, some bacterial pathogens, or herbicidal 

(2, 4-D) drift. The most familiar example is in crested 

cockscomb (Celosia cristata). The condition can occur 

in herbaceous and in woody plants. Flowers may crowd 

together in a mass at the end of the flat stem. 

Witches’-broom is the term used to describe an abnormal 

bushy growth of stems that seem to originate 

from one point. A dense cluster of branches with no 

apical dominance forms. There are various causes depending 

on the species of herb or woody plant afflicted: 

insects, bacteria, viruses, or fungi. 

COLOR CODE 

white: fleshy scale leaves (a), leaf buds (c), 

roots (j, q), potato rhizome and tuber 

yellow-tan: outer scale leaves (b) 

tan: onion stem axis, bud scale (d), scale 

covering (e, f), stem (o, r), tendril (t) 

light yellow: corm internodes, flower petals (i) 

green: leaf (g, n, s,), stem (m) 

purple-green: orchid pseudobulb (internode), stipe 

(h), leaf (l) 

purple-red: stolon (k) 

dark green: leaf (p) 

light green: stem (u), leaf (v), tendril (w)

Stem—Water Transport 

Transpirational “Pull” 

Water has a natural cohesiveness, surface tension, so 

will rise in a tube (capillary action), but not very high. 

How then does water rise from the soil to the leaves of 

tall trees? The air surrounding mesophyll cells in leaf 

tissue (see 22) has a humidity of 100% and, thus, the 

tissue air is saturated with water. Air outside the plant 

usually has a lower humidity unless it is raining. The 

evaporation of moist air as it escapes the leaf tissue, via 

the pores (stomata), provides a “pull” for water movement 

within the plant. 

Loss of water by evaporation from leaf surfaces is called 

transpiration. Water (a) moves upward in the plant 

from a region of higher water concentration in the soil to 

a region of lower water concentration, the dry air outside 

the leaves. 

Pathway of Water Transport 

Water (a) in the soil is absorbed by the epidermal root 

hairs (b). It then moves across the root through living 

cortical cells (c), is “filtered” through the semipermeable 

membranes of endodermal cells (d) passes through the 

pericycle (e), and enters the water-conducing cells (tracheids 

and vessel elements) of the xylem (f). Once in 

the xylem of the vascular system, water rises up the 

root to the stem and into the leaves. 

The maximum rate of water rise recorded in the roots 

of several oak species is 60 meters per hour. From 

the xylem, water enters the mesophyll tissue of the 

leaves and evaporates into the atmosphere via epidermal 

stomata when they are open. Much smaller 

amounts of water are lost from leaf cuticle and bark 

lenticels in the stems. 

Environmental Influences 

The rate of water transport in most plants is at a maximum 

during the daytime when air temperatures are 

high, relative humidity is low, and stomata are fully open. 

When the rate of water loss by transpiration exceeds the 

rate of water uptake from soil, the stomata usually close. 

Many succulent plants that live in the desert open their 

stomata only at night in order to conserve water. Thus, 

water transport and transpiration in these plants occur 

primarily at night. 

17 

COLOR CODE 

blue: arrows, water (a), xylem (f) 

colorless: root hair (b), cortex (c) 

tan: endodermis (d) 

yellow: pericycle (e) 

orange: phloem (g)

Stem—Food Transport 

Translocation is the term used to designate transport 

of soluble organic materials (food) from one part of a 

plant to another. These organic materials are mainly 

sugars (from photosynthesis) and amino acids and 

amides (products of nitrogen metabolism). Primarily, 

they come from leaves, which we call sources, and are 

transported to areas called sinks, where they are either 

metabolized or stored. Metabolic sinks include young, 

growing shoot tips (terminal and lateral), developing 

flower buds, growing stems, and elongating roots. Storage 

sinks include tubers, tuberous roots, bulbs, corms, 

fruits, or stem parenchyma tissue. The transport of organic 

solutes occurs in the phloem of the vascular system 

(see 11). 

At maturity, the sieve tube elements (see 8) of the 

phloem contain cytoplasm and cytoplasmic organelles 

but usually lack nuclei. Connecting strands, containing 

cytoplasm, pass through sieve areas on the end walls of 

adjacent sieve-tube elements, which provide channels 

for flow of organic solutes from one sieve tube element 

to the next. 

Solute Transport in the Phloem 

Münch Pressure-Flow Theory 

One of the most satisfactory explanations that has been 

proposed on long-distance transport of sugars in the 

phloem is the Münch Pressure-Flow Hypothesis. The 

diagram shows how it operates. Cells in the leaf (a) 

produce high amounts of sugar (b), which are actively 

(using ATP as an energy source) loaded into sieve tube 

elements (termed “phloem loading,” c) in the veins. 

Because of the high concentration of sugar and low 

concentration of water, water (d) enters the sieve tube 

elements (e) from the xylem by osmosis (see 5). This 

causes a high water pressure, which drives the sugar 

“sap” (b–d) through the sieve tube elements to a sink 

such as a fruit (f) or a storage root (g). At the sink, the 

sugars are actively “unloaded” (h) into cells where they 

are used or stored as starch (a glucose polymer) or 

fructan (a fructose polymer). The high concentration of 

water (d) that remains diffuses back into the xylem (i). 

18 

COLOR CODE 

orange: circles of sugar (b, c, h) 

blue: arrows of water (d)

Stem—Apical Dominance 

Apical dominance is the inhibition of the growth of axillary 

buds by the terminal bud of a shoot. When apical 

dominance is lost, axillary buds start to grow. This often 

occurs during flowering. In plants such as oats (Avena 

sativa) and sunflower (Helianthus annuus, a, b) with a 

very strong apical dominance, axillary buds may never 

develop during the vegetative phase of shoot development 

in both species, or in sunflower even when the 

plant is flowering (c). 

In plants such as wheat (Triticum) orColeus, where 

apical dominance is weak, axillary buds may start to 

grow. In Coleus, the lowest lateral buds on the primary 

shoot (d) develop into lateral shoots (e) first, and those 

near the top (f) last. 

In horticulture, “pinching off” the shoot tip of a dicot 

plant removes the terminal bud, breaking apical dominance, 

and results in a “bushy” plant as the axillary 

buds form shoots. Removing terminal buds produces 

thickly branched hedge plants, more flower shoots in 

plant such as chrysanthemums and asters and encourages 

more foliage growth in dicot houseplants. 

In grasses, the shoots that develop from lateral buds 

are called tillers (h). Cereal grasses, such as wheat 

and rice (Oryza), that produce tiller shoots during the 

vegetative phase of shoot development, produce more 

19 

“heads” of flowers (inflorescences) during the reproductive 

phase, and hence, yield more grain (i) per plant than 

cereals that do not tiller until the reproductive phase 

is underway or after harvesting, such as oats and annual 

rye. Even corn produces “suckers” (tiller shoots), 

which are often removed to enhance yield in “ears” of 

the main shoot. 

Apical dominance is regulated by two growth hormones: 

auxin (IAA, indole-3-acetic acid) from the terminal bud 

(k) and cytokinin (e.g., zeatin) from the roots. When the 

ratio of auxin to cytokinin decreases in favor of more 

cytokinins, apical dominance is lost and axillary buds 

are released to expand. 

To demonstrate how auxin is involved, three alike plants 

with strong apical dominance can be used. One plant 

is used as a standard of comparison, the control. In 

another plant, the terminal bud is removed and lanolin 

paste (l) is applied to the cut surface. For the third plant, 

the apical bud is also removed and lanolin paste containing 

0.1% auxin (m) is applied. After a period of time, 

the results show that in the control plant and the plant 

with the auxin application, the axillary buds (n) have 

remained suppressed. But in the plant without terminal 

bud or auxin application (lanolin only), apical dominance 

has been lost; the axillary buds are released and 

develop into elongated shoots (o). 

COLOR CODE 

dark green: shoot (a), leaves (b) 

yellow: flower (c), lanolin (l) 

purple: shoots (d, e, f), leaves (g) 

green: tiller (h), leaves (j), terminal bud (k) 

lateral buds (n), lateral shoots (o) 

tan: grain (i) 

orange: lanolin with auxin (m)

Stem—Growth Movements 

A tropism is growth in response to an environmental 

stimulus. Growth in response to unequal light intensities 

is called phototropism, while growth stimulation 

by gravity is called gravitropism. When movement is 

toward the source of stimulation, it is positive, and when 

away from the stimulation source, it is a negative response. 

Phototropic Responses 

Positive Phototropism. Shoots exhibit positive phototropism 

by growing towards light. When a dark-grown 

oat seedling (a) is exposed to a light source from the 

right, the shoot curves to the right (b) by cell elongation 

on the dark side. It was discovered that a transmissible 

substance must be produced by the tip of the outermost 

seedling leaf, the coleoptile (c). 

If a piece of mica (d) is inserted in the tip, no curvature 

occurs when a seedling is placed in a light source from 

the right. With the coleoptile tip cut off (e), the shoot 

(f) does not curve toward the light. It is known that the 

hormone, auxin, is produced in the coleoptile tip. When 

a tip (g) is placed on an agar block (h) with a glass 

cover slip (i) dividing it, a greater concentration of auxin 

(j) arrives on the side of the block away from the light 

source. 

Negative Phototropism. Roots (l) exhibit negative 

phototropism by growing toward the center of gravity. 

Skototropism is a form of negative phototropism ex- 

20 

hibited by tropical vine shoots in which initial growth is 

toward dark shadows cast by trees blocking light. After 

the vine has climbed the tree and reaches a lightexposed 

area, it becomes positively phototropic. 

Gravitropic Responses 

Orthotropism. (Ortho = straight, correct, vertical.) 

Shoots (m) not only curve toward light (positively phototropic) 

but straight away from the earth’s center of 

gravity (negatively gravitropic). Roots (n) and some fruit 

stalks show positive gravitropism by growing vertically 

toward the center of gravity. The root cap perceives the 

stimulus for the positive response, and auxin and other 

hormones regulate this growth process in the root. 

Plagiotropism. Plant parts that grow at an oblique angle 

from the vertical exhibit plagiotropism. Examples 

are lateral roots (p) and stems (q) that diverge from the 

main vertical axis. 

Diagravitropism. When plant parts grow at right angles 

to the line of gravity, they exhibit diagravitropism. 

Rooted rhizomes (s), stolons (v), horizontal branches, 

and horizontal leaf orientation are some examples. 

Agravitropism. Some plant parts are neutral to gravity 

and grow in various directions, such as the aerial roots 

of epiphytes (plants that grow upon other plants) and the 

flowering shoots of some plants that orient themselves 

in response to stimuli other than gravity. 

COLOR CODE 

white: shoots (a, b, e, f, g, m), roots (l, n, p), 

flower (y) 

tan: agar (h), seed coat (k), rhizome (s), 

shoot (t) 

green: leaf cutting (o), stem (q), leaves (r, w), 

shoots (u), stolon (v) 

red: strawberry fruit (x)

Leaf Types and Arrangement 

Persistence 

Deciduous. A perennial plant is one that lives more 

than two years. Leaves that fall off at the end of a growing 

period are called deciduous. Examples are found in 

maples (Acer), birches (Betula), and dogwoods (Cornus). 

Evergreen. Leaves that remain on a plant for more 

than a year are called evergreen. Pines (Pinus), spruces 

(Picea), rhododendrons (Rhododendron) are examples. 

Leaf Types 

Conifer. The leaves of conifers are needle-like (a) as 

on pines or scale-like as on junipers (Juniperus). They 

are usually evergreen, although some conifers have deciduous 

leaves such as larches (Larix). Each conifer 

leaf has a single vein. 

Ginkgo. This unique plant (see 72) has fan-shaped 

leaf blades (c) with dichotomous venation in which the 

veins branch into two equal or unequal lengths. The 

leaves are deciduous and shed within a 24-hour period. 

Dicot. Most dicot blades have pinnate (feather-like) venation 

(e) in which major veins diverge from one large 

mid-vein, with smaller network connections between. 

Some dicot blades have palmate (hand-like) venation 

(i) where several large veins diverge from the petiole 

to the margins. Some dicots have parallel venation. An 

example is plantain (Plantago lanceolata). 

Monocot. Most Temperate Zone monocots have narrow 

strap-shaped blades (f) with sheathing bases (g) 

surrounding the stem (h). With parallel venation, major 

veins arise at the base, remain more or less parallel, 

and converge at the tip with small vein interconnections. 

Some monocot leaf veins converge at the leaf margins 

instead of the tip, such as philodendron (Philodendron) 

21 

and some monocots have pinnate venation with Swiss 

cheese plant (Monstera) as an example. 

Leaf Attachment 

Petiolate. The leaf blade is attached to the stem by a 

stalk called a petiole (d). 

Sessile. When the leaf blade is attached directly to the 

stem without a petiole, it is sessile (a, f, n). 

Leaf Form 

Simple. A simple leaf has one blade, which may be 

broad (i) as in the maple leaf shown, narrow, or needlelike 

(a). 

Compound. A compound leaf is one that has two or 

more blade-like leaftlets such as sumac (Rhus, j, pinnately 

compound) or clover (Trifolium, k, palmately compound) 

attached to a petiole (d). 

Leaf Arrangement 

Opposite. Two leaves (l) emerge opposite each other 

on a stem. The example shown is milkweed (Asclepias 

syriaca). Generally maples, ashes, dogwoods, and 

members of the honeysuckle Family (Caprifoliaceae) 

have opposite leaves. MAD Cap is an easy way to remember. 

Alternate. In an alternate arrangement, single leaves 

(m) are attached spirally along the stem. Lamb’s quarters 

(Chenopodium album) is shown (see 88). Most 

genera have alternate leaves. 

Whorled. In a whorled arrangement, several leaves (n) 

emerge together around a stem node. Michigan lily (Lilium 

michiganense) is the example shown (see 128). 

COLOR CODE 

blue-green: blade (a) 

green: shoot peg (b), petiole (d), blade (l, n) 

dark green: blade (e) 

yellow: blade (c) 

light green: blade (f, m), sheath (g), stem (h), 

leaflets(k) 

orange: blade (i) 

red: leaflets (j)

Leaf Types and Arrangement

Leaf Tissues 

The leaf blade’s outer surface is epidermal tissue and 

the ground tissue within is photosynthetic mesophyll, interspersed 

with “veins” (vascular bundles) of conducting 

(vascular) tissue. Vascular connections between blade 

and stem pass through the petiole. 

Dicot Leaf 

Epidermis. There may be one or more layers of epidermal 

cells (a) with cutinized outer walls that form a 

waterproof outer surface. Stomata of guard cells (b) are 

present on the upper and lower surface or only on the 

lower surface as shown here. Various hairs and glands 

may also be present (see 10). 

Ground Tissue. The parenchyma cells of the ground 

tissue (c) are divided into palisade (d) and spongy (e) 

mesophyll. Usually the columnar cells (f) of the palisade 

layer lie under the upper leaf epidermis and contain 

most of the chloroplasts of the ground tissue. The 

spongy parenchyma (e) has irregular-shaped cells (g) 

with air spaces (h) between and lies above the lower 

leaf epidermis. 

Vascular Tissue. Four small vein transections are 

shown which are part of the vast, interconnecting network 

between major veins. A leaf vein (vascular bundle) 

usually has xylem (i) on the upper side and phloem (j) on 

the lower side. The reverse may be true in major veins. 

A layer of parenchyma cells called a bundle sheath (k), 

which functions in moving materials between the vein 

and the mesophyll tissue, usually encloses small veins. 

Monocot Leaf (Grass) 

Epidermis. Along with the epidermal cells (a), guard 

cells (b), hairs, silica, and cork cells, grass leaves have 

bulliform cells (l). The bubble-shaped, water-filled bul- 

22 

liform cells control leaf rolling (when the leaf is dry) and 

unrolling (when the leaf is turgid or filled with water). 

Under drought conditions, bulliform cells collapse and 

the leaf rolls up. 

Ground Tissue. In the temperate region, grass mesophyll 

(c) consists of only spongy parenchyma tissue 

whose cells contain chloroplasts—sites of photosynthesis. 

Vascular Tissue. Grass leaves have bundle sheaths 

(k) surrounding each vein. Sclerenchyma fiber strands 

(m) may be associated with the veins. (Leaf transection 

adapted with permission: Esau, K., Plant Anatomy, 

1967, John Wiley & Sons.) 

Conifer Leaf 

Epidermis. The usually small, triangular or flat “needle” 

leaves of conifers are adapted to dry conditions. 

Epidermal cells (a) have thick walls of cuticle, and 

sunken stomatal guard cells (b) overlapped on the surface 

by subsidiary cells (n). Stomata may be on one 

or all sides of the leaf surface. Under the epidermis 

may be a layer of thick-walled sclerenchyma cells called 

hypodermis (o). 

Ground Tissue. Mesophyll tissue (c) is not usually differentiated 

into palisade and spongy layers. Resin ducts 

(p) are present. 

Vascular Tissue. There are one or two veins in the 

center surrounded by transfusion tissue (q) and endodermis 

(r) containing tannins and resins. 

COLOR CODE 

colorless: epidermal cells (a), air space (h), 

bulliform cells (l), subsidiary cells (n), 

hypodermis (o), transfusion tissue (q) 

green: guard cells (b), monocot and conifer 

mesophyll (c) palisade parenchyma 

cells (f) 

light green: spongy parenchyma cells (g), bundle 

sheath (k) 

blue: xylem (i) 

orange: phloem (j) 

tan: sclerenchyma fibers (m), endodermis (r) 

yellow: resin duct (p)

Leaf Modifications 

Leaves may become highly specialized in function, exhibiting 

bizarre forms. Only a few of the many leaf modifications 

are shown here. 

Bract. Associated with a flower, bracts are reduced or 

modified leaves. Very small bracts are found in sedge 

and grass flowers (see 122, 123), while large colorful 

bracts (a) subtend flowers (b) such as Bougainvillea 

and poinsettia (Euphorbia). The spathe is an elaborate 

bract found in the arum family (see 127). 

Carnivorous Leaves. Carnivorous plants live in lownitrogen 

environments and enzymatically digest animals 

(mainly insects) in their leaves to supplement nutritional 

needs. The Venus’- flytrap (Dionaea)withatwolobed 

leaf blade (c, d) has trigger hairs (e) that set off 

a response that brings the spine-covered leaf margins 

(f) together in a closing trap. The leaf has a wide petiole 

(g). On butterwort (Pinguicula, see 10) and sundew 

(Drosera) leaves (h), long, sticky-bulbed, glandular 

hairs (i) entrap and digest insects. 

In pitcher-plants (Sarracenia), the hairy (j) lower surface 

of the leaf blade (k) is curved inward, forming a well 

of water and digestive enzymes. Nectar glands attract 

insects, while downward pointed hairs keep them in the 

leaf enclosure (see 91). The carnivorous leaf colors of 

the above examples attract flies (see 34). 

A water plant, bladderwort (Utricularia) has bait and 

trigger hairs (o) surrounding the mouth (p) of a bladder 

23 

(q), a modified leaf. Movement of the hairs entices small 

crustaceans to investigate. By negative pressure within 

the bladder, victims are sucked in and digested, sealed 

in by a trap door at the mouth of the bladder. 

Phyllode. This is a widened petiole that appears bladelike. 

In the acacia (Acacia melanoxylon) plant, some 

leaves consist of only petioles (phyllodes, r), while others 

develop compound leaflets (s). 

Spine. Spines are highly reduced leaves or stipules 

found on many herbs, shrubs, and trees. Often a plant 

exhibits a series of forms (homology) from leaf (t) to 

spine (u). 

Stipule. Usually in pairs, stipules (v) are basal appendages 

to the petiole (w). They may appear as hairs, 

leaves, tendrils, or spines. 

Succulent Leaves. An adaptation to dry environments, 

some plants store water in leaf mesophyll tissue. 

The epidermis may have thick cutinized and lignified 

walls to reduce water loss. In some succulents, the 

stomata reverse the usual condition and open only at 

night. The leaf epidermis (y) of living stones (Lithops), 

an example of mimicry, appears sand-colored. In 

the cut-away drawing, green mesophyll tissue (z) is 

exposed, surrounding the newly formed leaf in the 

center. 

COLOR CODE 

red: bracts (a), inner blade surface (c), 

hairs (i, j), veins (l) 

white: flower (b), hairs (e) 

yellow-green: blade margins (f), petiole (g), blade (d) 

green: leaf (h, n), leaflets (s) 

light green: petiole (m), blade (k), leaf (t), stipule 

(v), mesophyll (z) 

tan: hairs (o), bladder (q), spine (u), 

epidermis (y) 

dark green: petiole (r, w), blade (x)

Leaf—Photosynthesis 

Plant Energy Source 

Photosynthesis is the process in plants in which light 

energy is converted to useful chemical energy. In the 

process, carbon dioxide and water, in the presence 

of chlorophyll and light energy, form sugars, oxygen, 

chemical energy (ATP—adenosine triphosphate), and 

water. A general equation is shown. 

With the exception of fungi, photosynthesis occurs in 

all major groups of organisms discussed in this book, 

including certain bacteria. Most plants that photosynthesize 

have chloroplasts, in which photosynthesis occurs. 

Other cells, as in photosynthetic bacteria and bluegreens, 

have no chloroplasts. Instead photosynthesis 

occurs in pigments located in the cytoplasm. 

Significance of Photosynthesis 

Photosynthesis is responsible for the conversion of 

carbon from carbon dioxide into organic compounds 

in plants. It allows the plant to make organic building 

blocks for sugars, amino acids, nucleic acids, fatty 

acids, new cells, starch, protein, DNA and RNA, hormones 

and vitamins, and many secondary compounds. 

Without this photosynthetic process, life would not exist 

on earth. Plants provide, directly or indirectly, food 

for all animals and all of our atmospheric oxygen. They 

also “fix” CO2 in photosynthesis, which helps to reduce 

global warming. 

Photosynthesis consists of two basic parts: a series of 

light reactions and a series of dark reactions. In the light 

reaction (a), chlorophyll a (and accessory pigments) 

absorb light, which “excites” the electrons in the chlorophyll 

molecule. The electrons are passed along through 

a series of carriers (acceptors), and energy (ATP) is produced, 

which catalyzes the dark reaction. During the 

light reactions, water is split, giving off oxygen. 

24 

In the dark reaction (b), carbon dioxide, products of the 

light reaction (reducing power), and energy are used. 

Carbon dioxide is “fixed” or converted into a cyclic production 

of a series of carbon sugars, the most important 

of which ultimately is sucrose, made up of 6-carbon 

sugars, glucose, and fructose. 

C3 and C4 Plants 

In regard to photosynthesis, plants are divided into two 

types: C3 and C4 plants. In the leaves of C3 plants, which 

include most plants, light-driven carbon fixation reactions 

involve the formation of 3-carbon organic acids 

as the first stable products. In many tropical grasses 

C4 photosynthesis, such as sugar cane, corn, and 

sorghum, the photosynthetic process is more efficient. 

The grass bundle sheath (see 22) produces 3-carbon 

acids and sugars, whereas the mesophyll tissue produces 

4-carbon acids. These plants are more efficient 

in producing sugars because they have little or no sugar 

loss during respiration (a chemical release of energy 

from sugars) in the light (photorespiration). 

The illustration shows where the photosynthetic process 

takes place in the leaf (c) of a C3 plant. In the 

chloroplast (i), chlorophylls and accessory pigments are 

located in the thylakoids (j), where the light reaction 

takes place. Dark reactions take place in the stroma (k) 

of the chloroplast (see 3). 

Environmental Regulation of Photosynthesis 

Photosynthetic rate is regulated by the intensity of light, 

daylength, amounts of carbon dioxide and oxygen in 

the air (or water for water plants), temperature, and the 

level of air pollution. 

COLOR CODE 

green: light reaction (a), leaf (c), guard cells (e), 

palisade cells (h) with chloroplasts (i), 

thylakoid (j) 

gray: dark reaction (b), stroma (k) 

blue: water (xylem) in vein (d) 

orange: sugars (phloem) in vein (d) 

colorless: epidermis (f), spongy cells (g)

Leaf—Nutrient Deficiency Symptoms 

The essential elements that are required for the healthy 

growth of higher plants are carbon, hydrogen, oxygen, 

and those listed below. Plants take in carbon in the form 

of atmospheric carbon dioxide, obtain hydrogen and 

oxygen from water, and take up the remaining elements 

from the soil. By growing plants in an aqueous nutrient 

solution (hydroponics) and omitting an essential nutrient, 

specific deficiency symptoms can be observed. 

Nitrogen. Decaying organic matter provides soil nitrogen. 

Also, nitrogen-fixing bacteria on some plant 

roots convert atmospheric nitrogen into organic forms 

used by plants. Nitrogen deficiency results in yellowing 

(chlorosis) of older leaves. 

Phosphorus. Plants deficient in this element exhibit 

dark green older leaves and stunted growth. Red anthocyanin 

pigments sometimes accumulate. 

Potassium. This element is found in wood ashes 

(potash). Deficiency symptoms are exhibited in older 

leaves that yellow and have dead (necrotic) tissue in 

spots, and roots are easily infected with pathogenic organisms. 

Magnesium. A lack of magnesium results in a yellowing 

of the leaves between the veins with the tips and 

margins turning upward. 

Sulfur. Usually, a sulfur deficiency affects the younger 

leaves first with the veins becoming light green and a 

yellowing of the tissue between them. As sulfur compounds 

are found in most soils, this deficiency is rare. 

25 

Calcium. Lack of calcium affects meristematic regions, 

resulting in the death of terminal buds and root tips. 

Iron. A deficiency of iron results in a chlorosis of young 

leaves with the yellowing occurring between veins. 

Chlorine. Without chlorine, leaves wilt, turn yellow, 

show dead spots, and then become a bronze color. 

Roots become stunted and club-shaped near the tips. 

Manganese. Although a rarely found deficiency, without 

manganese, younger leaves form yellow speckles 

between the veins. 

Boron. Lack of boron produces death of shoot and 

root apical meristems, beginning with young leaves becoming 

light green at the base, and root tips becoming 

swollen. 

Zinc. A deficiency of zinc results in formation of small 

leaves and shortened stem internodes. The leaf margins 

may become distorted. 

Copper. A rare deficiency, lack of copper produces 

dark green, twisted young leaves, which often have 

dead spots. 

Molybdenum. Lack of this element produces chlorosis 

of old and midstem leaves, and eventually affects the 

young leaves. 

COLOR CODE 

green: terminal bud (a), new leaf (b), middle 

leaf (c), old leaf (d), veins (e) 

tan: roots (f) 

light green: chlorosis (g) 

yellow: late-stage chlorosis (h) 

brown: dead tissue (i) 

dark green: pigment accumulation (j) 

red-purple: anthocyanin pigmentation (k) 

red-brown: damaged tissue (l)

Flower Initiation in Response to Daylength 

Plants are classified as short-day, long-day, or dayneutral 

in terms of their flowering response to daylength 

(photoperiod). Most plants are day-neutral. They are 

not induced to flower by either long or short photoperiods. 

In the tropics, where photoperiods do not change 

nearly as much as in temperate regions, most plants 

are day-neutral or long-day in their response to photoperiod. 

Short-day Plants 

It has been found that rather than the length of daylight 

time, it is actually the length of the dark period 

(night length time) that induces flowering in short-day 

plants. If poinsettias are briefly illuminated during their 

long-night period, the flowering response is not induced. 

Short-day plants grow vegetatively (a) during 

long-day periods and flower (b) during short-day periods. 

Some examples of short-day plants are poinsettia 

(Euphorbia pulcherrima), thanksgiving cactus (Schlumbergera 

truncata), chrysanthemum (Chrysanthemum), 

lamb’s quarters (Chenopodium album), cocklebur 

(Xantium strumarium), strawberry (Fragaria), and many 

varieties of rice (Oryza). 

The nature of the flowering stimulus in short-day plants 

is not yet known. However, the stimulus most likely 

involves an interaction between flower-inhibitor and 

flower-promoter type hormones. The evidence that ini- 

26 

tiation of flowers involves hormones is that the signal 

can be perceived by one mature leaf. 

Using cocklebur plants, if one mature leaf (c) is exposed 

to short days while the rest of the plant is exposed to 

long days, flowering will result. Furthermore, by grafting 

a branch from a cocklebur plant given short days onto 

a cocklebur plant given long days, flowering is induced 

in the stems given long days. 

Long-day Plants 

Plants that require long days (short nights) for flowering 

include spinach (Spinacia oleracea), winter barley 

(Hordeum vulgare), winter wheat (Triticum aestivum), 

oats (Avena sativa), perennial ryegrass (Lolium 

perenne), clover (Trifolium pratense), coneflower (Rudbeckia), 

dill (Anethum graveolens), rose-of-sharon (Hibiscus 

syriacus), petunia (Petunia), and all biennials. 

Biennials are plants with a 2-year growth cycle. They 

require cool winter temperatures the first year, and long 

days the second year for flower induction. 

Some plants cannot be induced to flower by exposure to 

critical daylength periods until a certain age is reached. 

Depending on the species, some trees are not “flowermature“ 

until 5 to 40 years of age. For example, a sugar 

maple tree (Acer saccharum) may not flower until it is 

30 years old, but it can live 200 to 300 years. 

COLOR CODE 

red: tepals (d) 

green: stems (e, f, I), leaves (g, j), peduncle (k) 

tan: fruit(h) 

yellow: rays (l) 

brown: flowers (m)

Flower Structure 

Parts of a Flower 

Peduncle. The stalk that attaches the flower to the 

plant axis is called a peduncle (a). A pedicel is the 

stalk of a single flower in a cluster (inflorescence) with 

the pedicels attached to a peduncle ( see 98, 100, 109). 

Receptacle. The enlarged part of the flower axis where 

floral parts are borne is the receptacle (b). 

Sepals. The outermost whorl of floral parts are leaflike 

structures called sepals (c). While usually green, 

they may be colored in some species (see 129, 130). 

Sepals protect the developing flower in the bud stage. 

All of the sepals, collectively, make up the calyx. 

Petals. The second whorl of floral appendages are 

petals (d), which may be separate or partially fused 

together. Usually, they are showy and may be colored. 

All of the petals, collectively, make up the corolla. 

Tepals. When the calyx and corolla look alike and are 

petal-like, they are called tepals (see 126, 128). 

Perianth. This term is used to refer to the calyx and 

corolla together. 

Stamen. A stamen consists of a stalk-like filament (e) 

with an anther (f), made up of, usually, 2 pollen sacs, 

at the upper end. The connective (g) joins the pollen 

sacs containing pollen grains (h) (see 31). All of 

27 

the stamens, collectively, are termed the androecium 

(= male household). 

Pistil. A pistil is made up of stigma, style, and ovary. 

At the apex of the pistil is the stigma (i), where pollen 

grains adhere to the sugary, liquid excretions on the 

surface. Between the stigma and ovary is an elongated 

part of the pistil called the style (j). The ovary (k) consists 

of one or more carpels, which contain the ovules 

(see 28). Within the ovule (l), megaspores are formed, 

one of which develops into the embryo sac containing 

an egg (see 31). 

After fertilization, the ovules develop into seeds (see 

37). That part of the carpel where the ovules are attached 

is the placenta (see 28). A locule (m) is the 

chamber or space within a carpel. All of the pistils 

within a flower are called, collectively, the gynoecium 

(= female household). 

Number of Parts 

In a broad generalization, dicot flowers tend to have 

floral parts in whorls of 4 to 5 and monocots in series 

of 3. For example, a dicot flower might have 

4 sepals, 4 petals, and 8 stamens or 5 sepals, 5 petals, 

and 15 stamens. A monocot flower might have 3 sepals, 

3 petals, and 6 stamens. When observing flowers, it is 

interesting to determine number patterns. Numbers of 

floral parts are also used in “keying out” plants (plant 

identification). 

COLOR CODE 

light green: peduncle (a), stigma (i), style (j) 

white: receptacle (b), filament (e), ovary (k), 

ovules (l) 

green: sepals (c) 

optional: petals (d) 

yellow: anther (f), connective (g), pollen (h)

Flower Structure Variations 

Types of Flowers 

Unisexual (Imperfect). A unisexual flower has either 

staminate (male) (a) or pistillate (female) (b) structures. 

Bisexual (Perfect). A bisexual flower has staminate (a) 

and pistillate (b) structures. 

Monoecious (= of one house). An individual plant with 

separate (unisexual) staminate and pistillate flowers is 

termed monoecious (see 94). 

Dioecious (= of two houses). The term, dioecious, is 

used when a species has separate staminate-flowered 

plants and pistillate-flowered plants (see 105). 

Polygamomonoecious. An individual plant with bisexual 

flowers plus staminate or pistillate unisexual 

flowers is polygamomonoecious (poly = many; 

gamete = sex cell). 

Complete. A complete flower has staminate (a) and 

pistillate (b) structures, plus sepals (c) and petals (d). 

Incomplete. An incomplete flower lacks one or more 

floral parts. The incomplete flower shown lacks petals. 

Ovary Positions 

Superior. The superior ovary (f) of the pistil is above 

the site of attachment of other floral parts (stamens, 

sepals, petals). 

28 

Inferior. The inferior ovary (f) is below the site of attachment 

of other floral parts. 

Half-inferior or Half-superior. These are flowers that 

show varying degrees of ovary (f) position from partially 

superior to partially inferior. 

Placentation 

Axile. By fusion of 2 or more carpels (g), the ovules (h) 

are attached to the placenta (i) at the central axis (axile 

placentation). 

Free Central. Fused carpels (g) have lost their inner 

walls and the placenta (i) is located in the center (free 

central placentation). Examples are members of the 

pink family (Caryophyllaceae, see 87) and nightshade 

family (Solanaceae, see 111, pepper). 

Basal. The placenta (i) is located at the base of the 

ovary (basal placentation). 

Parietal. The placenta (i) is located on the inner walls 

of carpels, which do not extend into the center of the 

ovary (parietal placentation). 

COLOR CODE 

yellow: stamen (a) 

light green: pistil (b), ovary (f), carpel wall (g), ovules 

(h) 

green: sepals (c), peduncle (e) 

blue: petals (d) 

white: ovules (h), placenta (i)

Flower Development 

Flower Bud 

Early Stage. Above the peduncle (a), upright bracts (b) 

cover the sepals (c). The sepals enclose the developing 

petals (d), anthers (e), and the column of fused staminal 

filaments (f). 

Intermediate Stage. At this stage, the receptacle (g) 

expands and a young pistil (h) within the column (i) can 

be seen. At the top of the pistil, stigmas (j) form, the 

style (k) begins to elongate, and the ovary (l) enlarges. 

Late Stage. The folded petals (m) emerge from the 

sepals (n). Within, the filament column (p) has elongated 

and the stigmas (q) have emerged as the style (r) 

elongates. The superior ovary (l) has developing ovules 

(s) within the carpels. 

Mature Flower 

Bracts (b) are separate from the basally fused sepals (n) 

and the five petals (m) are expanded. The fully-formed 

fused filament column (t) protrudes above the petals. 

Anthers (o) are fully mature on short filaments (u), which 

separate from the column. Five stigmas (q) on a divided 

style (v) rise above the column. 

Anthesis. is the term used for the time when a flower 

comes into full bloom. It is a time when the flower is fully 

expanded. 

29 

COLOR CODE 

dark green: peduncle (s), bracts (b), sepals (c) 

light green: petals (d), filament column (i) 

white: anthers (e), filament column (f, p), 

receptacle (g), pistil (h), stigma (j), style 

(k, r), ovary (l), ovules (s) 

green: sepals (n) 

red: petals (m) 

yellow: anthers (o) 

dark red: stigmas (q), filament column (t), 

filaments (u), style (v)

Flower—Meiosis 

Each species has a specific number (2n) of chromosomes 

in the nucleus of each of its body (somatic) cells. 

Half of the chromosomes (1n) come from one parent 

and half (1n) from the other parent. For new body cells 

to form, 2n (diploid) cells divide by mitosis into more 2n 

cells. 

For an individual to become a parent, it must produce 1n 

(haploid) cells that can fuse with 1n (haploid) cells from 

another individual. The process of producing haploid 

cells from diploid cells is called meiosis. 

In higher plants, the end products of meiosis are haploid 

pollen grains in the anthers of the stamen and a haploid 

egg in each ovule of the pistil. In lower plants, the end 

products of meiosis are 1n (haploid) gametes (= sex 

cells). 

Stages of Meiosis 

Meiosis has 2 basic stages: (l), the reduction stage, and 

(II), the division stage. Unlike mitosis, during meiosis, 

chromosomes come together in pairs, called homologous 

pairs. Each chromosome of the pair has the same 

gene alignment and each represents a different parent. 

This pairing is significant because, during meiosis, 

“crossing over” (chiasmata) with an exchange of genes 

is possible (see 6). 

It is now obvious that the 2n (diploid) number is an even 

number for normal pairing to occur. The cells that undergo 

meiosis are called “mother cells.” Within each 

of the 2 stages of meiosis are 4 phases: prophase, 

metaphase, anaphase, and telophase. 

Prophase l. During early prophase, the 2n chromosomes 

(a, b, c) become visible as threads and then 

come together in homologous pairs. (For simplicity, 

only 3 pairs of chromosomes are shown within a nucleus.) 

Then each chromosome separates to form 

30 

2 chromatids held together at the centromere (d). 

“Crossing over” (e) of chromatid strands results in chiasmata 

(sing.: chiasma), which are visible sites of exchanged 

genetic material (f). 

Metaphase l. At this phase, the chromatids are positioned 

so that the centromeres are aligned on either 

side of the equatorial plane of the spindle apparatus 

(g). 

Anaphase l. Next, the paired chromatids separate and 

move to opposite poles (h). 

Telophase l. Lasting only a short time, telophase completes 

the reduction stage with the original number (2n) 

of chromosomes reduced to half (1n). 

Prophase ll. The second division stage of meiosis is 

essentially like mitosis (see 7). 

Metaphase ll. During this phase, the chromatids align 

in the center of the plane of the spindle. 

Anaphase ll. The centromeres (d) divide and chromosomes 

move to opposite poles (h) of the spindle. 

Telophase ll. By this phase, the chromosomes have 

completed their migration to the spindle poles. As a result, 

4 1n products are formed. The chromosomes (i, j, 

k) now have a different genetic makeup than the chromosomes 

of the original 2n cell. 

This meiotic description is characteristic of higher plants 

when 4 haploid products are formed. In flowering plants, 

in the ovule of the pistil, 3 of these nuclei usually disintegrate 

and the 4th divides (mitotically) repeatedly to form 

the nuclei of the embryo sac, one of which is the 1n egg 

nucleus. In the anther sac of the stamen, all 4 products 

of meiosis remain alive and develop into tetrads (4’s) of 

1n (haploid) pollen grains. 

COLOR CODE 

orange: chromosomes (a) 

yellow: chromosomes (b) 

green: chromosomes (c) 

purple: centromere (d) 

colorless: spindle (g) 

blue: chromosomes (i, j, k)

Flower—Pollen Development 

Young Stamen 

Once flower primordia are initiated, stamens begin to 

develop. The stamen in a flower consists of a filament 

(a) and an anther (b) with, usually, 2 pollen sacs 

(c). Pollen formation takes place within the chambers 

(locules) of the pollen sac (microsporangium). Each 

chamber is surrounded by a layer of cells called the 

tapetum (d), which functions as a source of nutrition 

for the 2n microspore mother cells (e). During a double 

division (meiosis), each mother cell forms a tetrad 

of 4 1n (haploid) microspores (f), which develop into 4 

pollen grains (male gametophytes). 

Pollen Grain 

In each pollen grain (g), nuclear division (mitosis) produces 

a large 1n vegetative nucleus (h) and a smaller 

1n generative nucleus (i), which divides to form two 1n 

sperm nuclei, usually after the pollen grain germinates 

to form a pollen tube (see 37). 

Mature Stamen 

Depending on the stamen type, the anther wall (j) spontaneously 

opens (dehisces) at a slit (k) to liberate pollen 

(l), or the anther wall breaks down, releasing pollen, or 

a portion of the anther lobe separates, leaving a pore 

(poricidal dehiscence). 

Pollen Grain Types 

Pollen grains have one or more furrows (m) or thin strips 

where the pollen tube may emerge. In some pollen 

grains, the pollen tube may emerge from a pore in the 

furrow or a pore not associated with a furrow. 

In flowering plants, the main types of pollen grains (n) 

are uniaperaturate with one furrow and triaperaturate 

with 3 furrows. Monocots and some primitive dicots 

have uniaperaturate pollen grains. Most dicots have 

triaperaturate pollen grains. Pollen grains vary from 

species to species in size, shape, and decoration of 

the outer wall (exine). Some pollen grains lack an exine. 

The study of pollen grains of past and present-day 

plants is called palynology. 

31 

COLOR CODE 

white: filament (a), microspore mother cell (e), 

microspore (f), anther wall (j) 

light green: anther pollen sacs (c) 

orange: tapetum (d), vegetative nucleus (h), 

generative nucleus (i) 

yellow: pollen grains (g, l, m,n)

Flower—Ovule Development 

Young Pistil 

When flowering is initiated, the pistil begins to develop 

in the center of the flower. It consists of stigma (at top), 

style and ovary (at base). The ovary (a) of the pistil 

has one or more separate or fused carpels (b). Within 

the carpel are locules (c) where ovules (d) develop. 

Ovule development begins with meiosis in a 2n megaspore 

mother cell (e) within the center portion of a young 

ovule (megasporangium). The megaspore mother cell 

undergoes a double reduction/division (meiosis) to form 

a linear tetrad of 1n megaspores. Of these, usually 

3 abort (f) with one megaspore (g) remaining. 

Embryo Sac 

The nucleus of the remaining megaspore divides repeatedly 

(mitosis) to form the 8 haploid (1n) nuclei of 

the embryo sac (female gametophyte, h). The central 

part of the ovule is vegetative tissue, nucellus (i). Surrounding 

the embryo sac are one or two layers of cells, 

the integuments (j), with a small opening at the base 

called the micropyle (k). 

Mature Ovule 

The 3 nuclei of most embryo sacs align into positions 

so that 1 near the micropylar end is the egg cell (l), 

2 are nuclei of synergid cells (m) with associated filiform 

apparatus (n), 2 are polar nuclei (o), and 3 are nuclei 

of antipodal cells (p). The mature ovule within the pistil 

consists of the embryo sac (h) surrounded by nucellus 

(i) and integuments (j). It is attached to the placenta (q) 

by a stalk called the funiculus (r). 

32 

COLOR CODE 

light green: ovary (a), integuments (j) placenta (q), 

funiculus (r) 

white: carpel (b), locule (c), ovule (d), aborted 

megaspores (f), synergids (m) filiform 

apparatus (n) polar nuclei (o), antipodals 

(p) 

gray: mother cell (e) megaspore (g), embryo 

sac (h) 

tan: egg (l) 

orange: nucellus (i)

Flower Pollination by Insects 

The transfer of pollen from an anther to the stigma 

of a pistil is called pollination. Some flowers are 

self-fertile and self-pollinated. Cross-pollination takes 

place when pollen is transferred to another plant. This 

provides genetic diversity. Within flowers of an individual 

plant, the time of pollen and stigma maturity may 

not coincide. Thus, all the pollen may be shed before 

the stigma matures and pollen must be transferred from 

another plant for fertilization to take place. 

Insect Pollination 

Although primitive seed plants, such as conifers, are 

wind-pollinated, fossil evidence shows that when flowering 

plants appeared, primitive insects such as beetles 

pollinated them. Beetles have biting mouthparts, 

and pollination of primitive flowers involved devouring 

pollen and other floral parts. Flowering plants developed 

structures that attracted other types of insects. As 

flowering plants diversified, there was a parallel diversity 

of insect specializations. Insects developed various 

mouthpieces, some in the form of hollow tubes (probosci). 

Nectar. In some plants, nectar (a sugar-water solution) 

was secreted. Then, concealed nectar at the bases of 

petal, stamens, or ovaries appeared in some plants. 

Some plants developed unisexual flowers (see 28) secreting 

nectar, although most flowers pollinated by insects 

are bisexual (see 28). Some flowers developed 

long nectar tubes or spurs (see 115, j), that attract insects 

with long probosci such as moths and butterflies. 

Petals. Many flowers secrete a strong scent. Scent 

produced in the petals differs among types of plants. In 

contrast to a green background, other colors appeared 

in flower petals. Some flowers, such as Iris, developed 

lines or hairs on petals (see 129, g) directed toward the 

nectar glands (see 101, k). These are commonly called 

nectar guides (see 130, n). 

33 

Specific insects were attracted to plants that developed 

corolla structures in the form of “landing platforms” 

(see 113, d), “overnight traps” (as in some arum family, 

Araceae, plants), and those that mimic the shape, 

scent, and color of female insects, a common strategy 

in the orchid family (Orchidaceae). 

Sepals. Some plant flowers developed stout sepals 

with overlapping bracts around the ovary. This is apparent 

in the arum family (see 127). 

Stamen. Plants produced pollen grains with a sticky 

coating and also the capacity to produce excessive 

pollen as food to lure pollinating insects. Some flowers 

developed fertile and sterile pollen on separate anthers 

to prevent wasteful expenditure of resources. 

Pistil. As plants diversified, there was a change in 

ovary position from an exposed superior position to one 

lower or below other floral parts (inferior ovary) (see 28). 

Pistils with inferior ovaries may have long styles, which 

elevate the stigma (see 113, sage flower). 

Butterfly-pollinated Flowers 

Butterflies are attracted to flowers aggregated in a head 

of many small flowers. The butterfly tongue is a long 

coiled tube adapted to sucking nectar from long-tubed 

flowers. Pollen is dusted on the tongue and head of the 

butterfly. The flickering appearance of flowers shaken 

by the wind is associated with the presence of nectar to 

butterflies. Flowers attractive to butterflies have sweet 

scents and are usually blue, dark pink, yellow-red, 

and purple. The illustrated example is red clover (Trifolium 

pratense) with a female black swallowtail butterfly 

(Papilio polyxenes asterius). 

COLOR CODE 

white: sepal ribs (a), petal tube (f) 

pale green: leaflet center (b) 

green: peduncle (c), leaflets (d), sepals (e) 

pink-purple: petal lobes (g) 

yellow: spots on abdomen (h), rows of outer 

forewing spots (i), row of outer hindwing 

cresents (j) 

orange: row of inner forewing spots (k), row of 

inner hindwing spots (l), single spot (m), 

row of spots between j and m 

blue: row of muted areas across hindwing (n)

Flower Pollination by Insects 

(continued) 

Bee-pollinated Flowers 

Bees perceive flowers that reflect yellow-green, bluegreen, 

blue-violet, and ultraviolet light. Petals of flowers 

with colored lines or dark marks guide bees toward 

nectaries. Rows of dots, stripes, crosses, and checks 

on flowers attract bees. 

The most common type of bee-pollinated flower has 

a “landing platform” such as the two-lipped (bilabiate) 

petals found in the flowers of the mint family (see 113, 

Lamiaceae), or falsely two-lipped petals such as the 

fused petals of banners and keel found in the pea family 

(see 100, Fabaceae). 

Bee-pollinated flowers have light, sweet, pleasant 

scents. Bees collect pollen (as a protein source to feed 

larvae) as well as sugar-rich nectar, which is converted 

to the honey on which they feed. Honeybees have a 

so-called pollen basket. Their bristly hairs attract pollen 

grains that they then brush with their legs into the basket 

on either side of their bodies. When baskets are tightly 

packed with pollen, they return to the hive. Of course, 

not all of the pollen is collected; much is brushed off on 

the next flower visited insuring pollination. 

Bees are the most efficient insect pollinators, as they 

will visit every flower in a mass of plants until the nectar 

is exhausted. Some flowers secrete nectar only at a 

specific time of day when fertilization is to take place; 

consequently, bees visit these flowers only at that time. 

Some flowers contain nectar in long spurs and are visited 

by long-tongued bees (see 115, Linaria). 

For an illustrated example, see iris family (120, Iridaceae), 

flag (Iris) with a bumblebee (Bombus affinis). 

34 

Moth-pollinated Flowers 

Highly scented and white, green, or yellow flowers are 

attractive to moths. Night-flying (nocturnal) moths pollinate 

night-blooming flowers. Nectar at the base of 

long petal tubes (a) is available only to insects such 

as moths with very long tubular mouth parts (f). Many 

moth-pollinated flowers are star-shaped with a central 

funnel to the nectary. 

The illustrated example is a tobacco flower (Nicotiana) 

with a Carolina sphinx moth (Protoparce sexta). 

(Moth adapted with permission from the National Geographic). 

Fly-pollinated Flowers 

Many flowers pollinated by flies have exposed nectar. 

Some have sweet odors, and other flowers have odor 

and color (pink, purple, green) of decomposing organic 

matter, which attracts flies. Usually flies are attracted to 

white, yellow, and yellow-green flowers. 

In the arum family (see 127, Araceae), the odor and 

color of the flower cluster (spadix), with its bract 

(spathe, n) attract flies. In some species, a fly visitor 

slides down the spadix, is trapped in the spathe, and is 

released within a day, carrying mature pollen. 

The illustrated example is a skunk cabbage (Symplocarpus 

foetidus) inflorescence with two syrphid carrion 

flies (Allograpta obliqua). 

COLOR CODE 

white: petal tube (a), fly wings (i), spadix 

flowers (p) 

yellow: stamens (b, o) 

green: calyx (c), peduncle (d), fly thorax (k), 

lines on spathe (m) 

light gray: moth eyes (e), moth tongue (f), moth 

thorax (g), moth wings (h) 

tan: fly eyes (j) 

orange: fly abdomen (l) 

purple: spathe (n)

Flower Pollination by Wind 

Wind Pollination 

From the fossil record, we learn that wind pollination 

was a later development in flowering plants. To change 

from pollination by insects to pollen transferred by wind 

currents, loss of color, petals, nectaries, scent, and the 

sticky covering on pollen grains became apparent. With 

the exception of sexual structures, flower parts developed 

that were much smaller in size. 

The stamens increased in size and number, and some 

stamens developed very long filaments. Huge amounts 

of tiny, dry pollen grains developed. Since wind is a 

chance pollinator, that is, more is better. The stigma 

of the pistil increased in size and often became feathery 

(plumose) or divided. The number of carpels in the 

ovary also increased in some flowers. 

Bisexual flowers changed to separate staminate (male) 

and pistillate (female) unisexual flowers and increased 

in number. Unisexual flowers tended to aggregate in 

clusters or to form catkins (aments). In some dicots, 

staminate and pistillate flowers formed on separate 

plants (dioecious) (see 106, staghorn sumac). 

Wind-pollinated Flowers 

Some of the monocot herbs that are wind-pollinated 

are members of the grass (Poaceae, see 123), cattail 

(Typhaceae), and rush (Juncaceae) families. Bisexual 

or staminate unisexual flowers are elevated on slender 

stalks above the vegetative parts of the plant. 

35 

Wind pollination is also found in trees, such as elms, 

ashes, and hackberries of the elm family (see 82, Ulmaceae). 

Birches, ironwoods, alders, and hazelnuts of 

the birch family (see 84, Betulaceae), beeches, oaks, 

and chestnuts of the beech family (see 83, Fagaceae) 

and poplars of the willow family (see 95, Salicaceae) 

are also trees with wind pollination. 

The notorious ragweed (Ambrosia) in the aster family 

(Asteraceae, see 119) is an obvious herbaceous dicot 

example. Hayfever sufferers are familiar with its windblown 

pollen. 

Willows (Salix spp.) have unisexual reduced flowers 

in catkins but have nectar glands and are insectpollinated. 

Staminate flowers, which form in clusters, 

swing loosely on an axis and open during the windy 

spring period before the leaves expand. Vestiges of bisexual 

flowers remain in some wind-pollinated flowers 

that have reduced, sterile structures of the opposite sex 

(see 105, maple family, Aceraceae). 

The illustrated example is a box elder (Acer negundo), 

which is dioecious. The flower in a cluster of staminate 

(male) flowers has pendant anthers (b) on a long pedicel 

(c). On a tree with pistillate (female) flowers, the 

compound leaves (I) begin to expand as the flower develop. 

The pistillate flowers has fused, lobed sepals (j), 

a double ovary (k) and divided stigmas(l). 

COLOR CODE 

tan: leaf scars (a, f) 

yellow: anthers (b) 

yellow-green: pedicel (c), shoots (d, g), bud scales 

(e, h), leaflet (i), sepals (j) 

tan-green: ovaries (k) 

white: stigmas (l)

Flower Pollination by Birds and Bats 

Bird and Bat Pollination 

A flower pollinated by birds or bats usually possesses 

both staminate (male) and pistillate (female) reproductive 

structures (bisexual). Some have sweet, fleshy 

bracts surrounding the flower as well as pollen and nectar. 

Others may have imitation pollen made of proteins 

and/or starch. 

While some flowers attract birds or bats, animals such 

as slugs, snails, earthworms, mice, rats, squirrels and 

opossums pollinate other flowers. Gerbils, mice and 

shrews pollinate various South African Protea species. 

These plants produce low-lying flowers of dull colors. 

The attraction for animals is food, i. e., copious amounts 

of nectar that contains not only sugar, but vitamins, 

amino acids and other nutrients. While an animal 

is gathering nectar, pollen grains with hooks and 

spines and sticky coatings adhere to the animal’s 

coat to be transferred to another flower resulting in 

pollination. 

Bird-pollinated Flowers 

Birds pollinate many tropical and subtropical plants. 

Flowers attractive to birds are usually bright red 

or orange. Some have striking color contrasts. 

Hummingbird-pollinated flowers are mainly red, a color 

not usually perceived by insects. Bird-pollinated flowers 

have abundant nectar and are without scent. Some are 

tube flowers with a basal swelling filled with nectar. The 

ovaries may be inferior or separated from the nectaries, 

36 

as in spur flowers, so that damage does not incur while 

the pollinator is visiting. 

Some bird visitors feed on small insects attracted 

by the nectar. Some bird-pollinated flowers are very 

large, while others are small. Some plants have sturdy 

perches near flowers, while others have freely swinging 

flowers, which attract hovering birds. 

Generally, bird-pollinated flower forms are of the twolipped 

(bilabiate) type, tubular flowers, flowers with a 

protruding bottlebrush stamen arrangement, or flowers 

with nectar in spurs. 

The illustration example is fuchsia (Fuchsia magellanica) 

with a Brazilian hermit hummingbird (Phaethornis 

eurynoma). 

Bat-pollinated Flowers 

Bats pollinate many large tropical herbs and trees. 

These flowers are usually arranged in a manner easily 

accessible to flying bats. Flowers attractive to bats 

bloom at night, have large amounts of nectar and pollen, 

are usually pale in color, may have a musky or fruity 

odor, and are strong enough to support a bat. Batpollinated 

flowers are bell-shaped, open saucer-shaped 

with many stamens, or possess suspended flowers with 

stamens bunched in a protruding brush. 

The illustration example is a saguaro cactus (Carnegiea 

gigantea) flower with a long-nosed bat (Leptonycteris 

sanborni). 

COLOR CODE 

green: peduncle (a), ovary (b) 

red: sepals (c ), filaments (f), style (h), bat 

tongue 

red-purple: petals (d) 

yellow: anthers (e), stigma (g), pollen(l), 

spines (p) 

yellow-green: bracts (o) 

light orange: area below bird’s eye (i), breast 

feathers (j), tips of bracts (n) 

white: unshaded areas of tail, near tail (k), 

tepals (m) 

light brown: remaining bird feathers, not colored 

above 

brown-orange: entire bat, except tongue and pollen

Flower—Fertilization and Embryo Development 

Fertilization 

Pistil. During pollination, pollen (a) from a stamen is 

transferred to a stigma (b). The stigmatic surface is usually 

covered with secretory cells (c) possessing copious 

amounts of sugars needed for growth of the pollen 

tube (d). The pollen tube grows within the style (e) to 

the ovule (f) in the ovary (g). There, it enters the embryo 

sac (h) at the opening (micropyle) between the 

integuments (i). Within the pollen tube are the 1n (haploid) 

tube nucleus (j) and two 1n (haploid) sperm nuclei 

(k, l). After entry into the embryo sac, the pollen tube tip 

bursts and discharges the 2 sperm nuclei. Simultaneously, 

one or both synergid cells (m) disintegrate (see 

32). 

Embryo Sac. Within the embryo sac double fertilization 

occurs. The egg (n) nucleus (o) fuses with one 

sperm nucleus (k) to form a 2n (diploid) zygote (q). The 

other sperm nucleus (l) unites with the 2 polar nuclei (p) 

to form a 3n (triploid) primary endosperm nucleus (r). 

Embryo Development 

Globular Stage Embryo. The primary endosperm nucleus 

divides repeatedly to form many 3n free, floating 

nuclei (s). Meanwhile, the zygote starts to divide, forming 

a basal cell (t), which develops into a suspensor 

(u) to elevate the developing embryo in the sac and 

to transport nutrients. An apical cell divides to form a 

globular mass of cells (v). 

Heart Stage Embryo. Walls develop around the free 

endosperm nuclei, forming the cellular endosperm (w). 

The endosperm cells contain stored food reserves such 

as hormones, starch, proteins, oils, and fats. In dicots, 

the embryo becomes heart-shaped with the formation 

of cotyledon primordia (x). 

Torpedo Stage Embryo. As the young embryo elongates, 

the vascular systems for the young root (y) and 

shoot (z) are formed. 

Mature Seed 

In the mature seed, the integuments (i) of the embryo 

sac have developed into the protective seed 

coat (testa). The embryo illustrated has 2 seed leaves 

(cotyledons, x) of a dicot. (Monocots usually have 1 

seed leaf or cotyledon, see 40, corn seed) 

37 

COLOR CODE 

yellow: pollen (a), pollen tube (d), tube nucleus 

(j) 

light green: stigma (b), secretory cells (c), style (e), 

ovule (f), ovary (g), integuments (i) 

gray: embyo sac (h) 

white: synergids (m), polar nuclei (p), zygote 

(q), embryo (t, u, v, x, y, z) 

tan: egg (n) 

red: sperm nuclei (k, l), egg nucleus (o) 

orange: endosperm (r, s, w)

Fruit—Dry Types 

A fruit is the seed-bearing structure in flowering plants 

(conifer seeds are borne in a cone). 

Indehiscent, Dry Fruit Types 

An indehiscent, dry fruit does not open at maturity. 

The tissues are composed of parenchyma and/or sclerenchyma 

(see 8) at maturity. 

Achene. An achene (a) is a type of one-seeded fruit 

with a thin wall (pericarp). 

Grain (Caryopsis). A grain (c) is a type of achene found 

in grasses (see 123, grass family, Poaceae), which originates 

from a superior ovary (see 28). 

Cypsela. An achene that originates from an inferior 

ovary, and commonly has a hairy pappus (d) present, 

is a cypsela (e). 

Nut. An achene-type fruit, the nut (f) is hard and “bony,” 

and may result from a compound ovary. 

Samara. The samara is a type of winged achene, 

which may be single, as in elm (Ulmus, h), or double, 

as in maple (Acer, i). 

Schizocarp. Carpels of a compound ovary break apart 

into mericarps (j), which function as achenes in the 

schizocarp type fruit. 

38 

Nutlet. A small nut is called a nutlet (k). 

Dehiscent, Dry Fruit Types 

A dehiscent, dry fruit opens to release seeds at maturity. 

The fruit splits under tension along definite lines or 

breakage points. 

Follicle. Composed of a single pistil, the follicle (l) splits 

along one line (see 77, Magnolia grandiflora). 

Legume. A legume (m) originates from one carpel, 

which splits along two lines, and is the fruit type of the 

pea family (see 100, Fabaceae). A type of legume, 

the seeds of a loment (n) are partitioned into sections. 

The carpel of a spiral legume (o) coils. 

Capsule. Capsules have more than one carpel and 

are classified by the mode of opening (dehiscence). 

The septicidal capsule (p) opens in the plane of carpel 

union. A loculicidal capsule (r) opens around a horizontal 

line. A poricidal capsule (t) releases seeds 

through pores at the top. 

Silique. A silique has 2 narrow pieces (valves,u) separated 

by a partition (replum, v). A rounded form is 

called a silicle (w, x). These are fruits of the mustard 

family (see 96, Brassicaceae). 

COLOR CODE 

tan: achene (a), cypsela (e), nut (f), 

schizocarp mericarps (j), nutlets (k), 

spiral (o), septicidal capsule (p), seeds 

(s), valve (x) 

white: grain (c), pappus (d), replum (v, w) 

red-brown: bracts (b) 

brown: cup (g), legume (m), loculicidal capsule 

(q), seeds (y) 

yellow-tan: single samara (h) 

green: double samara (i), circumscissile 

capsule (r), valve (u) 

yellow: follicle (l), loment (n), poricidal capsule (t)

Fruit—Fleshy Types, Compound 

Fleshy Fruit Types 

The ovary or fruit wall (pericarp) consists of an outer 

layer (exocarp), middle layers of parenchyma (mesocarp), 

and an inner layer (endocarp). The parenchyma 

tissues are filled with sugars, starch, and/or fats at maturity. 

Berry. The entire pericarp (b, c) of a berry is fleshy. 

There may be one or more carpels and seeds (d). 

Pepo. This berry with a hard-rind pericarp composed 

of exocarp (e) and endocarp is a pepo fruit. It is derived 

from an inferior ovary (see gourd family, Cucurbitaceae, 

94). 

Hesperidium. A leathery-rinded berry, the hesperidium 

exocarp (h) of compact collenchyma contains oil 

glands. There is a spongy mesocarp (i) and an endocarp 

(j), which produces juice sacs. This type, commonly 

called citrus, is found in the rue family, Rutaceae 

(see 107). 

Drupe. The drupe fruit ovary wall develops into a fleshy 

mesocarp (n) and a stony endocarp (o) over usually one 

seed. 

Pome. A pome has a pericarp of cartilaginous endocarp 

(r) lining the seed (q) cavities (locules), which are 

surrounded by fleshy parenchyma exocarp (s). Outside 

the inferior ovary wall is an expanded floral tube (t) of 

fleshy parenchyma. (For flower to fruit development, 

see rose family, Rosaeae, 99). 

Compound Fruit 

Aggregate Fruits. The separate carpel of one flower 

stays together as a unit in an aggregate fruit. Examples 

are an aggregate of drupelets (x), as in black raspberry 

fruits, an aggregate of achenes, as in strawberry fruits, 

and an aggregate of follicles (see 77, Magnolia grandiflora). 

Multiple Fruits. The carpels of separate flowers in a 

cluster stay together as a unit in multiple fruits as in a 

multiple of achenes in osage-orange and pineapple. 

39 

COLOR CODE 

tan: pedicel (a), peduncle (l, p), seed (d, k, 

y), endocarp (o) 

purple: exocarp (b) 

white: mesocarp (c, f, i, z), seed (g), exocarp 

(s), floral tube (t) 

green: exocarp (e), peduncle (v), sepal (w) 

yellow: exocarp (h) 

pale yellow: endocarp (j, r) 

red: exocarp (m), mesocarp (n), epidermis 

(u) 

brown: seed (q) 

dark blue: drupelet exocarp (x) 

yellow-green: epidermis (y)

Seed Structure and Germination 

A seed, which develops from an ovule, consists of a partially 

developed sporophyte plant (embryo) and none or 

various amounts of food storage tissue (endosperm) 

covered by a protective seed coat (testa). 

Dicot Seed 

The embryo usually has two seed leaves (cotyledons). 

As the bean seed is split in half, only one cotyledon 

(a) is shown. In the bean and pea seedlings, two cotyledons 

(a, b) can be seen. Between the cotyledons is the 

hypocotyl axis (c) with the shoot meristem (epicotyl) at 

one end, the root meristem at the other end. An undeveloped 

root (radicle, d) may be present. The plumule 

(e) of the bean seed will develop into stem (f) and leaves 

(g) in the seedling. 

Nutritive/food storage tissue (endosperm) sustains the 

germinating embryo until roots and leaves are functionally 

developed. Endosperm cells contain mostly starch 

with lesser amounts of proteins, oils, and/or fats. In bean 

seeds, the cotyledons, which occupy most of the space, 

store the food reserves, with the scant endosperm consisting 

mostly of protein. 

The seed coat (h) is made up of the ovules’ fused integuments. 

An opening (micropyle) between the integuments 

sometimes leaves a pore (i). Where the ovule 

was attached to the placenta, by a stalk (funiculus), 

there is sometimes a scar (hilium, j). Usually the seed 

coat is very thick and may be colored. 

Monocot Seed 

Usually monocot seeds have one cotyledon. A grain 

fruit (caryopsis) is used as a monocot example. The 

embryo includes one cotyledon called the scutellum 

(k), an outer protective cylindrical leaf (coleoptile, l), 

which encloses young leaves (m) over the shoot apical 

meristem (n), and a protective cap (coleorhiza,o)over 

the root apex (p). 

40 

The outermost layer of the endosperm, the aleurone 

(q), contains most of the protein of the seed, while the 

remaining endosperm (r) is mostly starch. In grains, the 

fruit coat (s) is made up of fused integuments and pericarp. 

In the monocot grain of rice (Oryza sativa), white rice 

(polished rice) is devoid of aleurone (“protein jacket”) 

and consists of embryo and starchy endosperm only. 

In contrast, brown rice (not polished) has the aleurone 

present and is thus much better nutritionally because 

the aleurone layer contains the bulk of the seed storage 

proteins (6 to 12 % of dry weight). White rice is primarily 

starch. 

Conifer Seed 

The embryo axis (t) consists of cotyledons (u) enclosing 

the shoot apical meristem at the tip, the hypocotyl, 

and the root apex (v) at the base. Conifer seeds have 

no endosperm; the embryo is surrounded by megagametophyte 

tissue (w) and enclosed by a seed coat (x). 

Germination 

Seed germination is the growth of the embryo, resulting 

in emergence of a shoot (epicotyl) and root 

(radicle). To germinate, the seed must be alive, not dormant, 

have a suitable temperature, adequate moisture, 

an oxygen supply, and for some species, light. 

Once the radicle has emerged from the seed coat, 

the seedling either develops with its cotyledons above 

ground (epigeous), as in bean (a) and pine (u), or below 

ground (hypogeous), as in pea (b) and corn (s). 

The cotyledons of epigeous seedlings produce chloroplasts 

and function photosynthetically until true leaves 

develop. Cotyledons of hypogeous seedlings provide 

food for the developing plants. 

COLOR CODE 

Seeds: white 

Seedlings: 

green: cotyledons (a, b, u), leaves and stipules 

(g), leaf (m), embryo axis (c, t), stem (f), 

coleoptile (l) 

tan: seed coat (h, x) 

white: roots 

yellow: fruit coat (s)

Major Groups; Geologic Time Scale 

Learning about the relationships of plants to each other 

involves the study of plant fossils (paleobotany), physical 

characteristics (anatomy), form (morphology), inheritance 

(genetics), chemical characteristics (physiology 

and plant biochemistry), and plant communities 

(ecology). 

Carolus Linnaeus (1707–1778) organized a system, 

that has since been expanded, for the classification of 

plants on the basis of their evolutionary relationships. 

Some groups of organisms studied by botanists are now 

no longer recognized as plants, as for example, bacteria, 

blue-green algae, fungi, and lichens. They are studied 

by specialists on bacteria and blue-greens (microbiologists), 

green, red, and brown algae (algologists), 

fungi (mycologists), and lichens (lichenologists). 

The Bacterial Group consists of bacteria, blue-greens 

and other microorganisms. In the past, blue-greens 

were grouped with algae. Now it is known that they are 

genetically more like bacteria. The cells of bacteria and 

blue-greens do not have organelles; instead, the cell 

membranes carry on many of the biological functions. 

There is no membrane-bound nucleus in the cell. This 

is termed prokaryotic (pro = before, karyon = nucleus). 

Nuclear material consists of strands of DNA 

(deoxyribonucleic acid, a molecule that constitutes the 

genetic information of a cell). Fibrils of DNA in the central 

region of a bacterial cell are designated by the 

term nucleoid. Asexual reproduction occurs by cell division 

or budding. Sexual reproduction is a recombination 

of genetic material. Most are microorganisms, smaller 

than the eukaryotic cells (eu = true, karyon = cell) of 

the other three kingdoms. 

Revision Group. Classification and relationships of 

molds, mildews, rusts, chytrids and allies, dinoflagellates, 

algal groups, and stoneworts and others are currently 

under revision. 

A characteristic in common in this group is the presence 

of nuclei (eukaryotic) in the cells. Many obtain food 

41 

(organic carbon metabolites) by photosynthesis within 

cell organelles called plastids. A flagellum (whip) for locomotion 

or feeding is present in many members. Most 

require oxygen (aerobic). They are aquatic. 

Fungi are organisms with nucleated cells (eukaryotic), 

that form resistant fungal spores, have cell walls 

composed of chitin, and do not have mobile cells at any 

stage. Fungi are found from the fossil record 450–500 

million years ago (the Ordovician period). 

Representative divisions in this book are black bread 

mold and allies, sac fungi, and club fungi. Lichen classification 

is a problem because lichens are an association 

of either a blue-green or a green alga with either a 

sac fungus or a club fungus. Lichens are included here 

with the fungi. 

Plants represented here include liverworts, hornworts, 

mosses, whisk ferns, clubmosses, spikemosses 

and quillworts, horsetails, ferns, and plants bearing 

seeds. Seed-bearing plants include the gymnosperms 

(= naked seeds) and the angiosperms (= enclosed 

seeds). 

Living gymnosperm groups are cycads, ginkgo, 

conifers, and gnetes. The angiosperm group consists 

of flowering plants. Characteristics of plants are covered 

in all three sections of the book. 

Geologic Time Scale 

Eras. The largest units of geologic time are known as 

eras; each encompasses millions of years. They are 

basically defined by biological events – the appearance 

or disappearance of major groups of organisms. These 

changes in biology are related to major geologic events. 

However, only the biologic changes are seen worldwide 

in the fossil record. 

Periods. Each era is subdivided into periods, and the 

periods are broken down into epochs; again their separations 

are most commonly based on fossils.

Geologic Time Scale 

Era Period Life 

Precambrian 

Precambrian The first fossil organisms of bacteria and blue-greens are found in rocks 

over 3,000 million years old, 

The earliest eukaryotic cells (true nucleated cells) are found in rocks 

about 1,000 million years old. These fossils are rare. 

600 million years ago ----------------------------------------------------------------------- 

Fossils of invertebrate marine animals are present. 

Paleozoic (Old Life) 

Cambrian 

500------------------------------------------------------------------------------------ 

The oldest fossils of fungi are from 450 million years ago and algae fossils 

Ordovician 

are common. Dinoflagellates are present. 

430------------------------------------------------------------------------------------ 

Silurian Oldest fossils of land plants are present. 

400------------------------------------------------------------------------------------ 

Land plants became abundant during the Devonian. Fossils of 

Devonian clubmosses, spikemosses, quillworts, giant horsetails, scouring rushes 

and ferns are found in this period. 

345------------------------------------------------------------------------------------ 

Mississippian 

During the Carboniferous (Mississippian and Pennsylvanian periods), 

310--------------------------there 

were vast forests of trees and swamps preserved now as coal. 

Pennsylvanian 

280------------------------------------------------------------------------------------ 

During the Permian, gnetes were present and true conifers emerged. 

Permian 

Ginkgos also originated during this period. 

225------------------------------------------------------------------------------------ 

Mesozoic (Middle Life) 

Triassic The Triassic was the time of reptiles and dinosaurs and the first mammals. 

There were forests of gymnosperms and ferns. Cycads were also present. 

180------------------------------------------------------------------------------------ 

The Jurassic was the “age of cycads” and it was a time when conifers 

Jurassic were distributed worldwide. Birds originated during this period. Reptiles 

were also dominant. 

136------------------------------------------------------------------------------------ 

Cretaceous Primitive flowering plants evolved during the Cretaceous. 

65------------------------------------------------------------------------------------ 

Cenozoic (New Life) 

During the Tertiary, flowering plants dominated the land. Later, grasslands 

Tertiary were apparent. The landscape has been dominated by herbaceous 

flowering plants ever since. 

2.5------------------------------------------------------------------------------------ 

Quaternary Humans are present.

Fossils 

Fossil Record and Appearance of Vascular Plants 

About 85% of earth’s geologic time is within the Precambrian. 

In the Precambrian, in rocks over 3,000 million 

years old, the first fossil organisms of bacteria and bluegreens 

are found. The earliest eukaryotic cells are from 

rocks about 1,000 million years old. These fossils are 

rare, and the early evolutionary history of non-vascular 

plants is obscure. 

The division that marks the end of Precambrian time 

and the beginning of the Paleozoic, about 600 million 

years ago, is recognized by the worldwide appearance 

of fossils of invertebrate marine animals. In the late 

Silurian period, the first vascular plants appear. Vascular 

plants are so designated because they possess 

specialized conducting tissues of xylem and phloem 

(see 9). 

Land plants became abundant during the Devonian. 

During the Carboniferous (Mississippian and Pennsylvanian), 

there were vast forests of trees and swamps 

preserved as what we know as coal. 

The Jurassic time of the Mesozoic was the “age of cycads” 

and it was a time when conifers became distributed 

worldwide. 

Primitive flowering plants evolved during the Cretaceous, 

and by the Tertiary time of the Cenozoic, they 

dominated the land. Later, grasslands were apparent 

and the landscape has been dominated by herbaceous 

flowering plants ever since. 

Fossil Evidence. A fossil represents evidence of past 

life. Fossils are usually found in nature as preserved 

remains or they may be just an imprint of an organism 

or part of an organism. Usually, vascular plant fossils 

occur as fragments. They often show alteration of original 

structures through damage by transport away from 

where they lived and when rock deposits were formed. 

During the process of fossil formation, plant parts commonly 

were compressed in soft sediment, which later 

hardened into rock, leaving an imprint such as a fern 

leaf. Or the plant was embedded in a soft matrix and 

later decayed as the rock formed, leaving a mold of its 

exterior. Or later, a hollow mold may have been filled in 

with mineral deposits forming a natural cast of the plant 

structure. 

42 

Embedded, “petrified” plant fossils are a result of cell 

contents being replaced by minerals while the cell walls 

are preserved. Thus, thinly cut sections reveal the microstructure 

of the fossilized plant parts. 

Paleobotany. This is the study of fossilized plants. As 

parts of plants are found, they are given “form genus” 

names. For example, a stem section, a leaf, a root, or 

a reproductive part such as a seed may all have different 

names, even after it is assumed that all belong to 

one extinct plant. An illustration of an entire fossil plant 

is a graphic reconstruction based on fossilized parts 

found. 

Of interest...organic evolution: origins and relationships 

or past and present life forms are better understood 

from their fossil record. By determining the ages 

of rock formations, it can be determined when plants 

first appeared and when they became extinct or yet 

survive. 

Economic: Coal deposits result from peat beds of decaying 

plants; an example is coal formed during the 

Carboniferous (Mississippian and Pennsylvanian). The 

term “carboniferous” is often used to refer to the two 

Paleozoic periods because of the extensive coal beds 

formed then. Pressure and heat from overlying rock 

sedimentation over millions of years compressed and 

converted the peat into coal. One of the methods for 

finding oil is the study of samples, obtained from drill 

holes, of microfossils of specific plants, pollen grains, 

and animals. 

Paleogeography. By studying the distribution of certain 

fossils over the earth’s crust, it is possible to determine 

ancient relationships of lands and seas. 

Paleoecology. Fossil organisms found together indicate 

ancient relationships, environment and climate.

Cordaites 

This conifer-like tree, which reached about 

30 meters in height, was prominent during the 

Carboniferous. Its trunk (a) was woody; the strapshaped, 

or sometimes fan-shaped, leaves (b) 

had parallel veins that branched dichotomously 

from the base. The leaves were up to a meter 

long. Reproductive structures (c) that resembled 

cones on an axis, bore male pollen sacs or 

female cone scales with ovules that developed 

into winged seeds after fertilization. (drawing after 

Grand ‘Eury, M. F. Cyrille, 1877) 

Williamsonia 

Cycadoid plants evolved in the late Carboniferous 

and became extinct during the late Cretaceous. 

One of these, Williamsonia, reached a height of 

2 meters. The plant had a columnar trunk (d) 

marked with old leaf base scars (e) and whorls 

of leafy fronds (f) similar to living cycads, although 

not related. Male pollen sacs and a female seedbearing 

organ were borne in a flower-like structure 

(g). (drawing after Sahni, 1932, Geologic Survey 

of India) 

COLOR CODE 

tan: trunk (a, d) 

green: leaves (b, f) 

yellow: reproductive structures (c, g) 

brown: leaf base scars (e)

Fossils (continued) 

Rhynia 

This plant lived only during the Devonian. Psilotum 

(see 64) and Tmesipteris are living plants that resemble 

Rhynia but are not known in the fossil record. 

Rhynia had simple hair-like rhizoids (a), a creeping underground 

stem (rhizome, b) that gave rise to upright, 

branching shoots (c) that reached 50 cm in height. As 

there were no leaves, it is assumed photosynthesis took 

place in the green stems. Spore cases (sporangia, d) 

containing spores were borne at the shoot tips. (drawing 

after Hirmer, 1927, R. Oldenbourg) 

Lepidodendron 

This tree reached 30 meters in height and was abundant 

during the Carboniferous. It is related to living lycopods 

(see 65). The stem bases (e) and stems (f) were dichotomously 

branched (fork of two branches of equal 

length). Diamond-shape leaf scars covered the outer 

surface of the upright stem (g) and upper branched 

stems. Extending beyond the leaves (h), cones (i) of 

sporangia with two kinds of spores (heterosporous condition) 

grew at the tips of stems. (drawing after Hirmer, 

1927, R. Oldenbourg) 

Calamites 

A tree that had secondary growth and thick bark, 

Calamites reached 10 meters in height. Although much 

smaller and herbaceous, living Equisetum (see 66) 

plants greatly resemble this ancient relative that lived 

during the Devonian and Mississipian periods. The upright 

stem (j) arose from an underground rhizome (k) 

and possessed roots (l) at the nodes. Stem nodes 

(m) bore whorls of stems (n). Stem ends had whorls 

of needle-like leaves (o). (drawing after Hirmer, 1927, 

R. Oldenbourg) 

43 

COLOR CODE 

white: rhizoids (a), rhizome (b, k) 

green: shoots (c), leaves (h, o), stem (j), 

whorls of stems (n) 

brown: sporangium (d) 

tan: stem bases (e), branched stems (f), 

upright stem (g), cones (i)

Blue-greens 

Fossil history of the blue-greens extends back to the 

Precambrian. They are found in water, in and on soil, 

on rocks, and in the atmosphere. Habitat temperatures 

range from 0 ◦ to 85 ◦ C. Some species occur in lichens, 

liverworts, water ferns, cycads, and flowering plants as 

symbionts (dissimilar organisms that live together and 

may, or may not, be beneficial to each other). 

Characteristics. The microscopic blue-greens have 

no membrane-bounded nucleus (prokaryotic, pro = before). 

[All plants and animals have membrane-bound 

cell organelles including nuclei (eukaryotic, eu = true).] 

The cell has a mucilaginous sheath of pectin that surrounds 

the cell wall and an inner cellulose wall. 

Cell contents (protoplasm) include nuclear material with 

DNA fibrils, chlorophyll a, and accessory pigments 

of blue (phycocyanins), red (phycoerythrin), orange 

(carotenes), and xanthophylls (yellow) colors. These 

pigments are involved in capture of light and subsequent 

formation of carbohydrates (photosynthesis). 

Cyanophycean starch is the storage product. 

Blue-green forms may be one cell (unicellular), colonial 

(cells held together by a gelatinous sheath), or filamentous 

(chains of cells called trichomes). They have no 

thread-like structures (flagella) for movement. 

Reproduction. Blue-greens have no known sexual reproduction. 

Reproduction of unicellular forms is by cell 

division in which the cell wall folds in and “pinches” 

the cell into two cells. Colonial and filamentous forms 

fragment into separate pieces. Filamentous forms have 

various specialized cells: an akinete is a resistant cell 

filled with food reserves, which can germinate to form 

a new filament; a transparent heterocyst functions in 

nitrogen-fixation, and frequently is located where the filament 

breaks. Some genera have exospores. These 

are cells that pinch off the filament. 

Of interest...ecosystem: blue-greens are primary colonizers 

on bare soil and rock; by forming mats that 

bind to the soil surface, they reduce soil erosion. As 

44 

nitrogen-fixers, they contribute to soil fertility (e.g., 

growing in rice paddies, Anabaena, in association with 

the floating water fern, Azolla, see 70, increases rice 

production). Blue-greens contribute to the water plankton 

food chain; reef building, in tropical waters bluegreens 

precipitate calcium carbonate (limestone) out 

of water and build up rock layers; toxins: “blooms” of 

dense concentrations in the sea kill marine fish, and in 

reservoirs, they may cause gastrointestinal diseases in 

cattle and humans. 

Synechococcus 

Structures of this unicellular spherical (coccoid) bluegreen 

include a mucilaginous sheath (a), cell wall (b), 

plasma membrane (c) and protoplasm (d). Reproduction 

is by binary fission (splitting into two). 

Cylindrospermum 

This filamentous blue-green has an akinete (resistant 

cell, e) and a heterocyst (spore-like cell, f) at the end of 

the trichome. 

Anabaena 

A heterocyst (g) is located near the center of the trichome. 

This filamentous genus is a frequent part of 

water “blooms.” In resevoirs it can cause bad odor and 

taste to water, killing birds and animals with endotoxin 

(released on decomposition). 

Gloeotrichia 

Colonies of trichomes are formed. The tapered trichome 

has a heterocyst (h) and an adjacent akinete 

(i). 

Hapalosiphon 

The trichome is branched, with a heterocyst (j) present. 

Branches form as the cells divide on a perpendicular 

plane. 

COLOR CODE 

white: sheath (a), heterocyst (f, g, h, j) 

tan: wall (b) 

blue-green: protoplasm (d) 

dark blue-green: akinete (e, i)

Slime Molds 

Even when organisms were grouped as either plants or 

animals, no one knew what to do with the slime molds. 

The creeping acellular phase is animal-like, while the 

reproductive structures that produce spores are plantlike. 

Now, true slime molds are recognized as a separate 

taxonomic group. 

Characteristics. There are about 450 species of slime 

molds distributed worldwide. Most live in shady moist 

woods on decaying wood, leaves, or moss. Some occur 

in open, but moist areas, such as lawn grass. They can 

be found, also, on damp bark mulch used in gardens. 

Their diet is bacteria, protozoa, fungal spores, and other 

minute organisms. The body of a slime mold is called 

a plasmodium (a), consisting of a membrane covering 

without cell walls, and containing many nuclei. Some 

plasmodia move in an amoeba-like fashion, flowing over 

surfaces, engulfing nutrients and other food sources. 

When temperature or moisture conditions are unfavorable, 

the plasmodium may convert to a hardened mass 

in a resting dormant condition called a sclerotium (b). 

Or with a temporarily dry environment, the plasmodium 

may mature to the fruiting stage. 

In the spring in north temperate regions slime molds can 

be found on wet rotting logs and examined with a hand 

lens. Throughout the summer, various forms of fruiting 

bodies can be discovered, such as those shown here. 

Reproduction. The life cycle consists of the plasmodium 

fusing with other plasmodia, increasing the number 

of nuclei, which divide simultaneously; engulfing 

food; and eventually, converting into fruiting bodies 

called fructifications. The three types of fructifications 

formed by various species are sporangia, aethalia, and 

plasmodiocarps. 

45 

A sporangium may have a stalk (h) or not, with a base 

called a hypothallus (i), and a wall of varying lime content, 

the peridium (g), that encloses the spores. Inside 

the peridium may be a non-living network of hairs, capillitium 

(f), that aid in spore dispersal. 

An aethalium is cushion-shaped with a peridium (o) 

enclosing the spores, such as Lycogala shown here. 

The third type of fructification is a plasmodiocarp, 

which retains the net-shape of the plasmodium. 

By reduction division (meiosis), 1n spores are produced. 

With favorable environmental conditions, the 

spore germinates into a myxamoeba without flagella 

(flagella, pl.; flagellum, sing. = whip-like structure for 

movement) or a swarm cell with flagella. These cells 

function as sex cells (gametes). Two cells fuse to form a 

2n zygote nucleus, which divides mitotically to develop 

into a plasmodium. 

Of interest...blue lawn infestation: Physarum 

cinereum; research material: slime molds provide 

pure, cell-less protoplasm for genetic, developmental, 

and cancer studies; ecosystem: primary decomposers 

in the forest food chain. 

COLOR CODE 

yellow: plasmodium (a), sclerotia (b) 

yellow-brown: dried plasmodium (c), capillitium (f) 

gray: stalk(d), peridium (e) 

tan: peridium (g), wood (y) 

dark brown: stalk (h), hypothallus (i) 

brown: spores (j) 

black: stalk (k) 

white: lime dots on peridium (l), 

hypothallus (v), stalk (w) 

dark brown: peridium (z, p), stalk (m, q) 

green: moss (n) 

pink: peridium (o) 

orange-brown: hypothallus (r), stalk (s), 

peridium(t),capillitium(u) 

iridescent (dots 

of green, 

red, yellow): peridium (x) 

orange: plasmodiocarp

Water Molds, Downy Mildews, 

White Rusts 

In this Oomycete group, organisms are microscopic 

and found in water and moist soil. The most advanced 

forms live entirely within a plant or animal host. They 

range from one cell to copious amounts of threadlike 

strands. Each strand of a threadlike tubular filament 

is called a hypha (pl. hyphae). A mass of 

hyphae is called mycelium. The cell wall contains 

cellulose. 

Reproduction is by oospores, sexually produced, nonmotile 

cells; and, asexually, by zoospores with two unlike 

flagella that are used for motility. 

Of interest...Albugo spp. (causes white rust of horseradish, 

cabbage, sweet potato, morning glory, spinach), 

Aphanomyces (causes root disease of sugar beets, 

peas), Phytophthora infestans (causes late blight of 

potato), Phytophthora ramorum (causes sudden oak 

death), Plasmopara viticola (causes downy mildew of 

grapes). Pythium debaryanum (causes damping-off of 

seedlings), Saprolegnia (causes disease of fish eggs 

and fish). 

Achyla 

The water mold illustrated here has separate male 

and female individuals. Eggs (a) are produced in an 

egg chamber (oogonium, b) on the hypha (c). From 

a male individual, antheridia (d) with male gametes 

branch from a hypha (e). After fertilization by a male 

gamete from the antheridium, an egg develops into a 

2n oospore (f). The oospore germinates to form a new 

body of hyphal stands (g) that produces biflagellated 

zoospores (h). 

46 

Chytrids and Allies 

The Chytridiomycetes are simple, microscopic organisms 

that live in both water and soil. They may be a 

single cell living within the cell of a host alga or higher 

plant or have true mycelia and live on the surface of a 

host. The motile cells have one whiplash flagellum. The 

cell walls of chytrids are made up of chitin, a tough resistant 

carbohydrate. Some have cellulose in their cell 

walls also. 

Of interest...Some chytrid parasites destroy algae. 

Some are parasitic on economic plants that include 

Physoderma (causes brown spot of corn), Synchytrium 

(causes black wart disease of potato tubers), and 

Urophlyctis (causes crown wart of alfalfa). 

Allomyces 

The 2n mycelium of this chytrid produces thin-walled 

spore-bearing structures called sporangia on hyphal 

strands (i). From a sporangium (j), 2n spores (k) 

emerge. Other, thick-walled sporangia (l) produce 1n 

spores (m) by meiosis (nuclear divisions that reduce 

the number of chromosomes by half). A 1n spore germinates 

into a 1n hypha (n), which produces 1n sex 

cells (gametes, o, p) in gametangia (q). Fusion of unlike 

gametes into a zygote (r) results in the germination 

of spore-bearing hyphae (i). 

COLOR CODE 

optional: egg (a) gamete (o, p), antheridia (d), 

oospore (f), zygote (r) 

gray: oogonium (b), hypha (c, e, g, i, n) 

yellow: zoospores (h, k, m) 

colorless: sporangium (j, l), gametangia(q)

Fungi 

Characteristics: Fungi are organisms without 

chlorophyll, and therefore, are dependent on other 

organisms for nutrition. A saprophytic fungus obtains 

food from dead organic matter. A parasitic fungus 

feeds upon a living organism, the host. Symbiotic 

fungi live in a mutually beneficial relationship with a 

host. A fungus associated with roots of a higher plant, 

called a mycorrhizal association, may be parasitic or 

symbiotic. In a symbiotic relationship both the plant and 

the fungus benefit. The fungal associate on plant roots 

produces digestive enzymes (proteases/peptidases) 

that release amino acids from proteins and absorb 

extra amounts of phosphorus from the soil, thence to 

the plant. The fungus benefits by using carbon—basal 

metabolites (e.g., sugars, amino acids, vitamins) from 

the plant roots. 

Carl Zimmer reported in 1997 that Suzanne Simard, 

a forest ecologist, discovered a fungal mycelium connected 

to several trees and even trees of different 

species. A forest community of plants can be ecologically 

interconnected to the point where removal of socalled 

weed trees disrupts the survival of the entire 

group of plants. She concluded that the fungus extracted 

carbon from healthy trees and shared it with 

trees growing under unfavorable light conditions. It is 

thus important to maintain diversity in forests for the 

health of all the plants. 

Fungi range in size from one-celled, microscopic organisms 

to masses of cells strung together in long filamentous 

strands. Each strand is called a hypha. The 

mass of hyphae that make up a fungal body is called 

mycelium. Cell walls are made up of chitin, which is 

hard and resists water loss. 

Reproduction. All fungi bear spores that germinate 

into strands of hyphae. The microscopic lower fungi 

mainly live within a host and reproduce mostly by asexual 

spores. Higher fungi have elaborate fruiting bodies, 

composed of hyphae, in which spores are produced. 

Sexual reproduction, used as the basis of fungal classification, 

commonly occurs once a year. 

Black Bread Mold and Allies 

Their sexual resting spores (zygospores) define zygomycete 

fungi. Another characteristic is the asexual, 

non-motile, reproductive spore. Of interest...Rhizopus 

stolonifer (causes black bread mold, strawberry leak, 

47 

and sweet rot of potatoes), Choanephora cucurbitarium 

(causes squash flower and fruit mold); Absidia sp., 

Mucor spp., Rhizopus sp. (can be fatal to the human 

nervous system). 

Mucor 

Hyphae (a) of compatible mating types develop side 

branches (b) that meet. A swelling or progametangium 

(c) is produced at each side. The walls (d) between the 

two break down. The nuclei from each progametangium 

fuse together and form a zygospore (e) that is held by 

suspensors (f). 

Sac Fungi 

Ascomycete fungi sexually produce usually 4 or 8 ascospores 

(g) within a sac sporangium called an ascus 

(h). Asexual reproduction occurs by breaking off 

(fragmentation) of mycelium, by splitting of one cell into 

two cells (fission), by budding of cells, and by formation 

of conidia. Fungi in the Hemiascomycetidae have 

little or no mycelia and the asci are not produced in 

a spore-bearing structure or fruiting body. Yeasts have 

evolved from several evolutionary lines, but are grouped 

together for convenience. They are found in sugary substances 

such as flower nectar and on the surface of 

fruits, in soil, in animal wastes, in milk, and in other substances. 

They have the ability to ferment carbohydrates, 

producing alcohol and carbon dioxide, as in wine and 

beer making. The leaf curl disease-causing fungi are 

classified with the yeasts, as both may form buds on the 

ascospores. Of interest...Saccharomyces cerevisiae 

(baker’s and brewer’s yeast), Taphrina spp. (causes leaf 

curl or peach, chokecherry, oak, witch’s broom of cherries). 

Saccharomyces cerevisiae Yeast 

Yeasts are microscopic, unicellular organisms (i). Asexual 

reproduction occurs by cell division and budding (j). 

Sexual reproduction, while rare, is by fusion of two cells 

to form an ascus (k) with 4 ascospores (l). 

Taphrina deformans Peach Leaf Curl 

Budding spores infect the peach leaf (m) producing 

more buds or mycelia, which penetrate the leaf tissue. 

The host tissue reacts to this infection by forming 

swollen, tumor-like masses (n) and by tortuous curling 

of the leaves.

COLOR CODE 

gray: hypha (a), tips (b), progametangium 

(c), zygospore (e), suspensors (f) 

yellow: ascospore (g, l) 

beige: cell (i, j) 

colorless: ascus (h, k) 

brown: masses (n) 

green: leaf (m)

Molds, Mildews, Morels (Sac Fungi) 

Usually members of this Euascomycetidae group have 

asci (sac sporangia) enclosed in a fruiting body called 

an ascocarp. A cleistothecium, a perithecium, and 

an apothecium are types of ascocarps. A cleistothecium 

(c) is an enclosed ascocarp composed of loose 

masses of hyphae with asci irregularly arranged within. 

A perithecium (h) is a vase-shaped ascocarp with a 

pore (ostiole, i) at the top. It may be embedded in a compacted 

mycelial structure (stroma, j). An apothecium 

is a cup-shaped ascocarp with asci lining the open surface 

(see 54, Xanthora, j). 

Of interest...molds: Aspergillus spp. (mold on 

bread, leather; causes human skin and respiratory 

disease), Aspergillus oryzae is used to make sake 

from rice in Japan, Claviceps purpurea (ergot of rye), 

Neurospora (pink bread mold), Penicillium italicum 

(blue mold on citrus fruits and preserves), P. digitatum 

(green mold on citrus fruits), P. camemberti (flavoring 

in Camembert cheese), P. roqueforti (for flavor in 

production of Roquefort cheese), P. notatum and P. 

chrysogenum (source of the antibiotic, penicillin); 

Rhizopus nigricans (black bread mold); wilts: Ceratocystis 

spp. (oak wilt, Dutch elm disease); blight: 

Endothia parasitica (chestnut blight); powdery 

mildews: Chaetomium (of clothes), Podosphaera 

leucotricha (of apple), Sphaerotheca pannosa 

(of roses); rot: Monilinia fructicola (brown rot of 

stone fruits such as peach, plum, cherry, apricot); 

wild: Helvella and Gyromitra (false morels), 

Morchella (morel), Tuber maganatum (white truffle), 

T. melanosporum (black Perigord truffle), Verpa (bell 

morel). 

Truffles form a mycorrhizal association with roots of 

oak, hazel, poplar and many other trees. Of the 200 

species, two edible species are found in France and 

Italy. Hunters using trained pigs and dogs gather them. 

Small mammals (chipmunks, voles and squirrels) feed 

on truffles and disperse fungal spores in their fecal 

matter. 

Penicillium 

Asexual reproduction occurs by microscopic spores 

called conidia (a) formed on the side of a hyphal strand 

(b). By subjecting conidia of Penicillium chrysogenum 

to ultra-violet irradiation, surviving colonies have a high 

yield for penicillin production. It is a naturally occurring 

antibiotic. Discovery came when it was observed that 

48 

in Petri dishes, bacterial colonies died when “contaminated” 

with Penicillium. 

Microsphaera alni Powdery Mildew of Lilac 

The microscopic fruiting body is a cleistothecium. The 

wall (c) has been broken to reveal 2 asci (d) with ascospores 

(e). Appendages (f) aid in spore dispersal. 

Diatrypella 

In this fruiting body, asci (g) line perithecia (h) with terminal 

pores (i). They are embedded in a hyphal stroma 

(j). 

Morchella Morel 

Easily recognized, this edible mushroom is prized for its 

distinctive flavor. Apothecia with asci line the cavities (k) 

of the spongy-looking fruiting body. In spring, morels are 

a mushroom hunter’s favorite find in northern deciduous 

wooded areas. 

Claviceps purpurea Ergot of Rye 

An ascospore germinates to form a mat of mycelium 

on a rye flower (see 123). Instead of a rye grain (m) 

developing, the fungal mycelium forms an overwintering 

asexual mass—a dark, hardened sclerotium (n). 

This sclerotium contains ergot alkaloids that poison cattle 

when grazing and humans when eating contaminated 

rye flour products. Also in humans, ergot causes 

gangrene. 

Xylaria Dead Man’ Finger 

Perithecia are embedded in the outer wall of the stroma 

(o) or “finger,” which develops on rotten, burned wood. 

Mycelial filaments (p) are shown. 

Daldinia concentrica 

A vertical section reveals perithecia (q) lining the outer 

stromatic surface (r) of this cushion-shaped fruiting 

body. 

Geoglossum difforme, Microglossum rufum 

Earth Tongues 

Apothecia of asci form on the surface of the club-shaped 

fruiting bodies (s, t).

COLOR CODE 

yellow: conidia (a), ascospore (e), ascus (g) 

colorless: ascus (d), pores (i), filaments (p), 

perithecium (q) 

gray: hypha (b), perithecium (h), stroma (o) 

black: wall (c), stroma (j), fruiting body (s) 

white: appendages (f) 

beige: fruiting body (k, l) 

gold: grain (m) 

dark brown: sclerotium (n), stalk (u) 

purple: stroma (r) 

orange-red: fruiting body t) 

green: moss (v)

Rusts, Smuts, Jelly Fungi 

(Club Fungi) 

For club fungi sexual reproduction results in usually 4 

basidiospores (a) produced on the outside of a microscopic 

club-shaped sporangium called a basidium (b). 

When basidia are borne in a fruiting body, it is called 

a basidiocarp. Familiar forms are mushrooms, shelf 

fungi and puffballs. Also included are rusts, smuts, jellies, 

stickhorns, bird’s-nest fungi, coral fungi and earth 

stars. There are many edible species; however, there 

are no rules, only myths, for distinguishing poisonous 

from edible fungi. There are about 22,000 species of 

basidiomycetes. 

Rusts (Uredinales). Fungi in this order are obligate 

parasites (require living hosts) on plants. No fruiting 

bodies are produced. Classification is based on 

the presence of teleutospores, representing the overwintering, 

resting stage. Many rusts attack only specific 

plants. Some require two hosts to complete their 

life cycles. For example, wheat rust alternates between 

wheat (Triticum) and barberry (Berberis)—unrelated 

hosts. This is called heteroecism (different homes). 

Of interest...Cronarium ribicola (white pine blister 

rust with currants and gooseberries as the alternate 

hosts), Gymnosporangium spp. (rusts of juniper, apple, 

hawthorn, and pear), Piccinia spp. (rusts of wheat, barley, 

oats, rye, and hollyhock), Uredinopsis osmundae 

on alternate hosts of balsam fir (Abies balsamea) and 

cinnamon fern (Osmunda cinnamomea). 

Gymnosporangium juniperi-virginianae 

The life cycle of this fungus is completed by alternation 

of the fungus between apple (Malus) and red cedar (Juniperus 

virginiana) host plants. The cedar apple gall (c) 

is a mass of mycelium on cedars (d). During spring, 

gelatinous structures, telia (e), expand with water uptake 

(e.g., from rainfall) and protrude from the surface. 

Inside a telium are hundreds of teleutospores, basidial 

structures that produce basidiospores after germination 

on apple trees. 

Smuts (Ustilaginales). Smuts form masses of black, 

sooty-looking teleutospores. Smuts are similar to rusts 

but do not need living host material and can be grown in 

the laboratory. Of interest...Tilletia foetia (bunt or stinking 

smut of wheat), Ustilago spp. (smut of corn, oats), 

Urocystis cepulae (onion smut). Ustilago maydis (corn 

49 

smut) is sold as a gourmet food called “corn mushroom.” 

Economically, smuts cause extensive damage to crops 

and consequent reductions in yields. 

Urocystis cepulae Onion Smut 

Black teleutospores (f) form an infestation on bulbs of 

onions (g). This is commonly seen on commercially sold 

onions. 

Jelly Fungi (Auriculariales). Fruiting bodies of gelatinous 

material are produced. When wet, basidia are 

formed. Most genera are saprobic, living on dead organic 

matter. A few genera are parasitic on mosses 

and flowering plants. Of interest...Herpobasidium deformans 

(blight of honeysuckle). 

Auricularia auricula Ear Fungus 

The gelatinous fruiting body (h) resembles a human ear. 

Jelly Fungi (Tremellales). Fruiting bodies are gelatinous 

with leaf-like folds that vary in color with species 

from white, pink, yellow, and orange to red. 

Tremella mesenterica 

This jelly fungus (i) is found on hardwood tree bark (j). 

Some species are edible. 

Jelly Fungi (Dacrymycetales). Waxy, bright-colored 

gelatinous fruiting bodies are produced. The yellow coloring 

is due to β-carotene pigment. They grow on living 

or dead trees. 

Dacryopinax spathularia 

This jelly fungus (k) is found on rotting wood (l). 

COLOR CODE 

yellow: basidiospore (a), onion (g) 

tan: basidium (b), fruiting body (h) 

orange: telium (e), fruiting body (k) 

brown: gall (c), wood (l) 

green: cedar (d) 

pale yellow: fruiting body (i) 

gray: bark (j)

Gill Fungi 

Gill, Pore, Coral, and Toothed Fungi (Agaricales). 

In this order, a basidium usually produces 4 basidiospores, 

which are forcibly discharged from the fruiting 

body. Fruiting bodies may occur in forms commonly 

known as mushrooms, toadstools, shelves, corals, and 

toothed fungi. 

A “spore print” (basidiospore collection) can be made 

by placing a fruiting body cap with gills or pores half on 

white paper, half on black paper. If dark spores are discovered, 

use an entire cap on white paper and if light 

spores use black paper. Spore color is useful for identification. 

If can be white, pink, yellow, brown, purple, or 

black. 

Of interest...food: Agaricus campestris (commercial 

mushroom), Calvatia gigantea (giant puffball), 

Cantharellus cibarius (chanterelle), Lentinus edodes 

(shiitake, high in vitamin B12, cobalamin; grown commercially 

on white oak logs to produce fruiting bodies 

for up to 10 years after inoculating the mycelium 

in holes drilled in the logs. Logs are stacked crisscrossed 

like Lincoln logs in the shade of deciduous 

forests and watered frequently with sprinklers. This 

technique is widely used in Korea and now in the U.S. 

by Korean entrepreneurs.), Pleurotus ostreatus (oyster 

mushroom, this mushroom is grown commercially 

on vertically stacked sections of American elm, Ulmus 

americana, trunks covered with black plastic film.); 

wild: Amanita verna (destroying angel, contains a 

deadly poison that destroys liver and kidney cells), 

Armillaria mellea (honey mushroom, causes root rot of 

trees, exhibits bioluminescence or “fox-fire” in myceliapenetrated 

organic matter), Boletus edulis (porous 

mushroom), Ganoderma applanatum (shelf or bracket 

fungus, a type of artist’s fungus, so called because 

marks made on the smooth white underside will remain 

when the mushroom dries), Marasmius oreades 

50 

(fairy ring mushroom), Polyporus sulphureus (sulfur 

mushroom, causes wood rot of trees), P. squamosus 

(heart rot of trees), Psilocybe spp. (hallucinogenic 

mushrooms). Psilocybe mushrooms in Mexico are collected, 

dried, and served in pairs by women in all-night 

religious ceremonies of Amerinds, as documented by 

the famous Harvard University botanist, Charles Evans 

Schultes. 

Amanita muscaria Fly Amanita, Fly Agaric 

The fruiting body of a gill mushroom begins as a mass of 

hyphal cells and enlarges into a “button.” At this stage, 

the fruiting body is surrounded by a universal veil (d). 

As expansion of the gills (lamellae) takes place, the veil 

is broken. The veil may remain as patches or scales (b) 

on the cap (pileus) and as veil remnants (c) or as a cup 

(volva) at the base of the stalk (stipe). 

Some species of agarics also have an inner or partial 

veil (d) between the developing stalk (e) and gills (f). 

When the partial veil is broken upon expansion of the 

gills, it may remain attached to the stalk as a ring (annulus, 

g) or remain attached to the margin of the cap, 

hanging down as a curtain, as in Cortinarius. 

The microscopic basidia are borne on the inner surface 

of the gill. Individual cap (h) color in this species 

varies from white, yellow, and orange to red. This is 

a poisonous mushroom, found mostly in mycorrhizal 

association (see 12) with roots of aspen and conifer 

trees. 

Cortinarius 

Remains of the partial veil, which hangs down from the 

cap as a curtain (cortina), form web-like lines (i) on the 

stalk (j). As the cap expands, gills (k) are exposed. This 

fruiting body was found in a beech-maple forest. 

COLOR CODE 

white: scales (b), veil remnants (c), partial 

veil (d), stalk (e), gills (f), annulus (g) 

orange-red: cap (h) 

light tan: stalk (j), gills (k) 

yellow: cap margin (l) 

yellow-brown: cap center (m)

Gill and Pore Fungi 

Agaricales (continued) 

Coprinus comatus Shaggy Mane 

As the white fruiting body matures, the gills undergo 

self-digestion with black basidiospores released in an 

inky black fluid. This mushroom is found in lawns, golf 

courses and fields and is edible and preferred in the 

button stage before dripping black fluid. Remnant of a 

veil (a) remains on top. Caution: when eating this mushroom, 

alcoholic drinks should not be taken; otherwise, 

you can become quite ill! 

Chantharellus cinnabarinus Cinnabar 

Chanterelle 

Basidiospores are produced on blunt gills (b). With age, 

the cap (c) becomes funnel-shaped on the fruiting body 

stalk (d). This mushroom is edible and found in forests 

throughout the United States and Canada. It is considered 

a gourmet treat, sold in grocery markets and used 

in restaurant offerings. 

Russula emetica Emetic Russula 

The fruiting body has a stout stalk (e) supporting a bright 

red cap (f) with white, brittle gills (g). This fragile fruiting 

body is probably poisonous. 

Suillus americanus 

Instead of gills, this mushroom has fleshy pores (h) and 

is therefore designated as a bolete. Basidia line the 

inner surfaces of layers of tubes with pore openings. 

The fruiting body is fleshy and decays quickly. Brown 

scales (i) dot the yellow cap (j). It is edible, but little 

flesh remains after the tubes have been removed. 

51 

COLOR CODE 

light tan: veil remnant (a) 

dark orange: gills (b), cap (c), stalk (d) 

pale pink: stalk (e) 

red: cap (f) 

white: gills (g) 

yellow: pores (h), cap (j), stalk (k) 

brown: scales (i) 

green: moss (l)

Pore, Coral, and Toothed Fungi 

Agaricales (continued) 

Coriolus (Polyporus, Trametes) versicolor 

Turkey-tail Fungus 

In polypore ( = many pores) fungi, basidia are formed on 

the inner surface of leathery pores (a) on the lower portion 

of the fruiting body (b). This fan-shaped bracket fungus 

is found on rotting wood. The bands of tan, brown, 

white are like the colors of a turkey’s tail feathers, and 

thus account for the common name. 

Fomes formentarius Rusty-hoof Fungus 

This perennial polypore adds new growth (c) yearly to 

the woody bracket-type fruiting body (d). It is parasitic 

on birch (Betula) and beech (Fagus, e) and some other 

hardwood deciduous trees. It is shaped like a horse’s 

hoof and is common in northern temperate zones. 

Irpex lacteus Crust Polypore 

A crust-like fruiting body (f) of this polypore grows on 

the lower surface of dead tree limbs (g). 

Clavulinopsis fusiformis Coral Fungus 

The fruiting body (h) in this coral fungus is simple and 

unbranched. 

Ramaria stricta Straight Coral Fungus 

This coral fungus has a more complexly branched fruiting 

body (i). It is usually found on rotting beech (Fagus) 

wood. 

Hericium Toothed Fungus 

Basidia are produced on downward-pointed, tooth-like 

projections on the fruiting body (j). It is found on dead 

deciduous hardwood trees. 

52 

COLOR CODE 

tan-brown-white bands: fruiting body (a, b) 

rust (yellow-brown-red): new growth (c) 

dark and light gray bands: fruiting body (d) 

brown: bark (e) 

yellow-tan: fruiting body (f, i) 

gray: bark (g) 

orange: fruiting body (h) 

white: fruiting body (j)

Puffballs, Stinkhorns, 

Bird’s-nest Fungi 

Puffball Fungi (Lycoperdales). Spores are dispersed 

by wind from puffball fruiting bodies. An inner fertile portion, 

called the gleba, is composed of basidiospores 

and sterile thread-like structures (capillitia). Powdery 

masses of spores are exposed when the puffball wall 

(peridium) disintegrates, or emerge in a cloud from 

an opening (ostiole) when the flexible peridium is disturbed. 

Of interest . . . Calvatia gigantea (giant puffball) found 

in mostly open or sometimes wooded areas and after 

rains in late summer or early autumn and is edible when 

pure white inside, Geastrum and Astraeus (earthstars), 

Lycoperdon (stalked puffball). 

Geastrum Earthstar 

This type of puffball has a star shape when the rigid 

outer wall or peridium (a) becomes wet and splits 

open. An inner flexible peridium (b) is exposed. A single 

pore (ostiole, c) for spore dispersal occurs at the 

center. 

Lycoperdon Stalked Puffball 

At maturity, a powdery gleba of spores (d) puffs out of 

an ostiole (e) in the peridium (f) due to rain drops or 

other physical disturbances. 

Stinkhorn Fungi (Phallales). Basidiospores are 

formed within a gleba. A receptacle, bearing the gleba, 

emerges from a protective enclosure, the peridium. As 

the gleba breaks down, the basidiospores are exposed 

in a gelatinous mass at the top of the stinkhorn. The 

foul smell of the mass attracts flies, which disperse the 

spores. 

Of interest...Dictyophora (collared stinkhorn), Clathrus 

(net stinkhorn), Mutinus (dog stinkhorn), Phallus 

(common stinkhorn) 

53 

Dictyophora duplicata Collared Stinkhorn 

At the egg stage, the peridium (g) encloses the gleba 

(h) where basidia and basiospores are formed. The receptacle 

(i) and stalk (k) will enlarge and emerge from 

the peridium, which remains at the base. 

Mutinus caninus Dog Stinkhorn 

From the broken peridium (k), a pink stalk (l) emerges. 

The dark pink receptacle (m) at the top of the fruiting 

body is covered by a green, slimy mass (gleba, n) of 

spores. 

Bird’s-nest Fungi (Nidulariales). The fruiting body 

appears as a hollow nest filled with egg-like peridioles, 

which contain basidiospores. The nest acts as a 

splashcup. Raindrops cause the periodioles to bounce 

out of the fruiting body. The periodiole’s sticky covering 

adheres to nearby surfaces where the spores are then 

released. This type of fungus is often found on rotting 

bark mulch used in gardening and on deciduous forest 

duff litter. 

Of interest . . . Nidularia (white bird’s-nest fungus), Crucibulum 

(common bird’s nest fungus), Cyathus (striate 

bird’s-nest fungus). 

Crucibulum vulgare Common Bird’s-nest 

Fungus 

This genus is often found on wood chip (o) paths and 

on the forest “floor.” Small peridioles (p) are formed in 

the nest-like fruiting body (q). 

Of interest . . . many of these fungi are important in 

forest tree communities in causing the breakdown of 

leaf/twig litter and dead tree branches to form organic 

humus (like compost) over the forest floor. This forms a 

great substratum for forest tree seed germination and 

subsequent development of seedlings. 

COLOR CODE 

tan: peridium (a, b, f, g, q) 

green-brown: gleba (h, n) 

white: receptacle (i), stalk (j), peridium (k), 

periodiole (p) 

light pink: stalk (l) 

dark pink: receptacle (m) 

brown: wood chips (o)

Lichens 

A lichen is an association of a fungus (mycobiont, 

mykes = fungus + bios = life) and an alga (phycobiont, 

phykos = alga + bios = life). The fungus is an 

ascomycete or a basidiomycete. The algal partner is either 

a blue-green or a green alga. The association can 

be parasitic, in which the fungus eventually kills the algal 

cells; or it can be mutualistic, in which both fungus 

and algal cells benefit. Mutual benefits include algal nutrition 

that benefits the fungus because of the presence 

of chlorophyll for photosynthesis in the alga. And protection 

for the smaller alga is provided by the fungus. 

Lichens can tolerate harsh conditions such as dryness, 

arctic cold, and bare rock habitats. They possibly live 

for thousands of years. 

Characteristics. The upper cortex (a) is the outer 

protective layer with fungal hyphae gelatinized and 

cemented together. Next is the algal layer (b). Most lichens 

are associated with the unicellular green alga, Trebouxia. 

So far, over 30 genera of algae have been found 

associated with lichens. Most of the lichen body (thallus) 

is made up of medulla (c) with hyphae loosely interwoven. 

The medulla retains moisture and stores food. 

The thallus may take different forms. Crustose lichens 

are extremely flat and only ascocarps (fruiting bodies 

of the fungus, see 48) may be visible. (See drawing 

opposite of Graphis scripta). They are found on 

rocks and trees. The medulla may be embedded in 

rock surfaces. Foliose lichens have a leafy thallus 

and may have a compacted lower cortex (d) and rootlike 

anchoring devices called rhizines (e). (See drawings 

opposite of Xanthoria and Physcia aipolia.) Fruticose 

lichens with three-dimensional projections, called 

podetia, arise from a scale-like, loosely-attached (squamulose) 

base. (See drawings opposite of Cladonia 

cristatella and Cladonia pyxidata.) 

Reproduction. Various vegetative structures may be 

found on lichens, such as soredia and isidia. Soredia 

originate in the algal layer as masses of algae cells with 

a few gelatinized hyphae erupting through cracks in the 

surface cortex. By a process of breaking off, new lichen 

thalli are formed. An isidium is a projection on a foliose 

or fruticose lichen that serves as a vegetative propagule 

when broken off. Depending on the type of fungus, 

fruiting bodies with ascospores or basidiospores are 

produced. 

Lichens also have asexual structures called pycnidia, 

flask-shaped structures that produce microconidia. The 

54 

fungal spore or microconidium must form an association 

with an appropriate alga in order to live. 

Of interest . . . arctic animal food: Cetrarias, Cladonia 

spp. (reindeer mosses), Usneas; human skin rash: Evernias, 

Usneas; dye: Letharia, Ochrolechia, Parmelia, 

Roccella; ecosystem succession role: lichens are 

often the first colonizers of bare substrate, breaking up 

rocks, due to their secretions of lichen acids; thalli form 

an anchor base for later colonizing plants. 

Sac Fungi: Euascomycetidae (Lecanorales) 

Graphis scripta Script Lichen 

Found on hardwood trees, this crustose lichen thallus 

(f) has dark eruptions of apothecia (g). 

Xanthoria 

Found on rotten wood, the thallus (h) of this foliose 

lichen has apothecia composed of gray-green 

receptables (i) with brightly colored ascopsore layers 

(hymenia, j). 

Physcia aipolia Blister Lichen 

This foliose lichen has a white-spotted thallus (k) with 

apothecia emerging from the surface cortex. The fertile 

layer of asci (hymenium, l) is gray with a gray-green 

receptacle (m). 

Cladonia cristatella British Soldiers 

The fruticose podetium (n) arises from a squamulose 

thallus (o). Red apothecia (p) dot the top of the podetia. 

Cladonia pyxidata Pyxie Cup 

The fruiticose podetia (q) resemble pyxie cups arising 

from a squamulose thallus (r). Brown apothecia (s) dot 

the cup rims. 

COLOR CODE 

gray: cortex (a, d), thallus (f), hymenium (l) 

green: algae (b) 

white: medulla (c) 

black: rhizines (e), apothecia (g) 

gray-green: thallus (h, k, o, r), receptacle (i, m), 

podetium (n, q) 

yellow-orange: hymenium (j) 

red: apothecium (p) 

brown: apothecium (s)

Dinoflagellates 

Fossils of dinoflagellates extend back to the Ordovician 

time of the Paleozoic. Most are marine. 

Characteristics. These microscopic organisms are 

unicellular and are usually motile due to the presence 

of a pair of unequal flagella. There are diverse forms. 

Nutrition varies from self-feeding (autotrophic) tomutually 

beneficial (mutualistic) to dependency upon a 

host (parasitic). Pigments are chlorophylls a and c, 

carotene, and the xanthophyll, peridinin, which gives 

a gold-brown color to the organisms. Starch is the primary 

stored food. 

The nucleus is large and the chromosomes remain visible 

at all stages (see 6), while the nuclear membrane remains 

intact. Some dinoflagellates have light-sensitive 

eyespots. Other marine species are bioluminescent: 

when cells are vigorously agitated, they give off flashes 

of light. 

Reproduction. Asexual reproduction occurs by cell division 

and cyst formation. Sexual reproduction is by 

sex cells (gametes) that look alike (isogamy) or unlike 

(anisogamy). 

Of interest . . . “blooms” or “red tides:” under optimal 

conditions rapid reproduction produces heavy concentrations 

of dinoflagellates that color the ocean red, redbrown, 

or yellow; toxins: these “blooms” can be toxic 

55 

to other organisms in different ways: killing only fish, 

killing mainly invertebrates, or not killing but concentrating 

their toxins in bivalve mollusks. The toxins produced 

by species of Gonyaulax are thousands of times 

more potent than cocaine, and may cause human death 

within 12 hours after consumption of affected bivalves, 

but in low concentrations, their toxin usually produce 

severe digestive upsets. 

Dinophyceae. This class of dinoflagellates is made 

up of biflagellated motile cells. One flagellum is coiled 

around the transverse girdle groove (cingulum), providing 

a rotating movement. The other flagellum is located 

in a longitudinal groove (sulcus); it functions as a propellant 

from the posterior end. 

Gymnodinium 

The name means “naked whorl,” as it is without armored 

plates. Structures shown are the girdle groove (a) with 

flagellum (b) and the sulcus groove (c) with flagellum 

(d). Many chloroplasts (e) are visible. 

Ceratium 

The name means “horned.” Armored plates (f) ornamented 

with pits cover the organism. Structures shown 

are the girdle groove (g) with flagellum (h) and the sulcus 

groove (i) with flagellum (j). 

COLOR CODE 

gold-brown: chloroplasts (e), plates (f)

Golden Algae, Yellow-green 

Algae, Diatoms 

This diverse group of algae has several common features: 

a complex carbohydrate food reserve called 

chrysolaminaran (leucosin); more carotene pigments 

than chlorophylls, thus the gold and yellow-green colors; 

and chlorophylls a and c. The pigment, fucoxanthin, 

occurs in some of the divisions. Forms range from 

amoeboid cells, flagellated cells, filaments, to parenchymatous 

thalloid types. 

Golden Algae (Chrysophyceae). Members in this 

group live mainly in fresh water. There are a few marine 

forms. Some have cell coverings that may contain 

silica. Two-part resting spores (statocysts) are formed 

when unfavorable conditions occur. Asexual reproduction 

is by fragmentation and production of an asexual 

reproductive cell (zoospore). Sexual reproduction is not 

well-known. 

Dinobryon 

This fresh water alga forms free-swimming colonies of 

biflagellated cells. The protoplast (a) is connected by 

a thin strand to its protective covering: a transparent, 

open-ended, vase-shaped lorica (b). The protoplast has 

2 flagella (c) of unequal length, an eyespot (d) and a 

chloroplast (e). 

Yellow-green Algae (Xanthophyceae). Fresh water 

habitats are typical for this group. They form a scum 

in standing water, and some occur on the surface of 

moist mud and on tree trunks. There are less than 100 

known species. 

Vaucheria 

This alga is a branching filament (f) containing many 

chloroplasts (g). It may form mats under moist, greenhouse 

clay pots. The filament has no cross-walls except 

where reproductive chambers are formed. Reproduction 

is by asexual zoospores and by the sexual union 

of a small motile sperm with a large non-motile egg 

(oogamy). An antheridial branch (h) containing sperm 

cells (i) forms laterally on a filament. A biflagellated 

sperm cell swims to a pore (j) in the oogonium (k) to 

fertilize the egg (l). The fertilized egg develops into an 

oospore (m), which remains in the oogonium as a resting 

spore until germination occurs. 

56 

Diatoms (Bacillariophyceae). Two hundred surviving 

genera of unicellular diatoms are known, with as many 

as 100,000 species. Diatom walls (frustules) have the 

structure of a narrow box with a lid. The lid, called the 

epivalve, fits over the box or hypovalve. The overlapping 

area is the girdle region. Reproduction is by cell division. 

It involves separation of the epivalve and hypovalve, 

with new, smaller container walls being formed. When 

an ultimate, minimum size reduction is reached, new 

cells are formed by the fusion of the protoplasm of two 

cells. Diatoms also have sexual reproduction. 

Of interest . . . ecosystem: diatoms, the major component 

of plankton—which form the base of aquatic food 

chains, are the single most important group of algae. 

In relation to other families, diatoms also supply the 

major percentage of the world’s oxygen supply. They 

are affected by temperature, pollution, and light. Some 

characteristic species of diatoms and other algae are 

indicators of polluted water, while other species are indicative 

of clean, non-polluted water; fossils: diatomaceous 

earth is represented by the silica remains of diatoms; 

it is used for filters, abrasives, insulation, in pavement 

paints, and as an indicator of oil- and gas-bearing 

formations. 

Pinnularia 

The epivaluve (n) portion fits over the hypovalve (o) as 

shown in this diatom diagram. 

Asterionella 

This diatom forms a star-shaped colony of cells (p). 

Coscinodiscus 

Surface striations (q) of puncture holes mark the wall 

(r). 

COLOR CODE 

red: eyespot (d) 

yellow: protoplast (a), diatoms (n, o, p, q, r) 

yellow-brown: chloroplast (e) 

yellow-green: filament (f), oospore (m) 

tan: sperm cells (i), egg (l)

Red Algae 

The red algae, with about 400 genera, are mostly marine 

with only a few known freshwater genera. Most are 

found in tropical areas where they occur at great depths 

or along intertidal regions. 

Characteristics. Their color varies greatly depending 

on the amount of pigments and can range from shades 

of green, red-brown, bright red, blue, and purple-blue to 

black. Usually, the green pigments, chlorophylls a and 

d, are masked by the phycobilin pigment (red phycoerthyrin 

and blue phycocyanin). Other pigments include 

carotenes and xanthophylls (see 4). 

Red algae are relatively simple vegetative organisms 

but have complex reproductive systems. The primary 

food reserve is floridean starch (a polysaccharide = 

carbohydrate made up of many glucose units). There 

are a few microscopic unicellular forms, but most have 

branched filaments or flat leaf-like forms. 

Reproduction. Asexual reproduction occurs by fragmentation 

and production of vegetative spores. Red algae 

are divided into two subclasses. In the more primitive 

Bangiophycidae, sexual reproduction is mostly absent. 

In the more advanced Florideophycidae, sexual 

reproduction is oogamous: non-flagellated male gametes 

(spermatia) are carried by water to a stationary 

female gamete-bearing structure called the carpogonium. 

Of interest . . . colloids: Chondrus crispus (carrageenan, 

used as a stabilizing agent in milk products, 

jellied foods, cosmetics, insect sprays, and water-based 

paints), Gloiopeltis (funori, used as a water-soluble 

sizing in water-based paints and as a flexible starch in 

laundering); agar: Gelidium (agar, used as a culture 

medium in microbiology, as non-irritant bulk in human 

intestinal disorders, and to make pill capsules); coral 

57 

reefs: Corallinna, Lithothamnium, and Galaxaura 

accumulate calcium carbonate, which contributes to 

reef-building; ecosystem: red algae provide food for 

marine animals; human food: Chrondrus crispus (Irish 

moss), Porphyra (nori), Palmaria (dulse). 

Porphyra Nori 

This genus, in the subclass Bangiophycidae, has a leafy 

thallus (a) with rhizoidal cells at the base for attachment 

to rocks. 

Polysiphonia 

Placed in the subclass Florideophycidae, this genus 

has a filamentous thallus (b) constructed of many (poly) 

tubes (siphons, c); hence its name. Male gametophyte 

individuals produce special branchlets called trichoblasts 

(d), that bear spermatia (e). Female gametophyte 

individuals produce urn-shaped structures called 

cystocarps (f), which contain egg cases (carpogonia). 

After fertilization and maturation, carpospores (g) are 

released. Carpospores develop into a tetrasporophyte 

generation, producing tetraspores that germinate into 

male or female gametophytes (gamete-bearing). Both 

the tetrasporophyte and the gametophyte generations 

have the same external filamentous appearance. 

Of interest ...to preserve filamentous marine plant 

specimens, place the plant in a large shallow pan of 

water and allow it to float naturally. Then slide art paper, 

bond paper, or, ideally, rag paper under the specimen. 

Slowly lift the paper with the plant on top and drain excess 

water off one end. Blot the bottom of the paper on 

newsprint, then place plant-on-paper in a single folded 

sheet of newspaper. Stack with blotters and newspaper 

and press with weights or place in a plant press 

until dry. 

COLOR CODE 

red-purple: thallus (a) 

red: thallus (b), tubes (c), trichoblast (d, e), 

cystocarp (f), carpospores (g)

Green Algae 

Green algae constitute a very ancient group of plants 

with fossils occurring back to early periods of the Paleozoic 

era. They are mainly freshwater plants, but 

also occur in saltwater, in soil, on tree bark, and on 

snow. 

Characteristics. Green algae forms are unicellular, 

colonial, filamentous, membranous (resembling) 

leaves), and tubular. The cells have many of the 

organelles found in cells of higher plants, including 

a rigid cell wall; a nucleus with one or more nucleoli; 

a large vacuole; well-organized chloroplasts; 

pigments of chlorophylls a and b, carotenes, and 

xanthophylls; self-feeding nutrition (autotropic); and 

pyrenoids associated with starch formation. Motile 

forms usually have two whiplash flagella of equal length. 

There are many varying types of asexual and sexual 

reproduction. 

Of interest . . . phylogeny: green algae are considered 

to be on the direct evolutionary line to higher vascular 

plants; ecosystem: they contribute to the freshwater 

plankton of the food chain. 

Note: Of the 450 genera, the few illustrated here are 

microscopic, with the exception of Acetabularia, which 

is macroscopic. 

Chlamydomonas 

This unicellular alga is motile by means of two flagella 

(a). The cup-shape chloroplast (b), that contains a red 

eyespot (c) and a pyrenoid (d), surrounds the nucleus 

(e). 

Eudorina 

Sixteen cells make up this coenobium (a colony 

of a fixed number of cells). A gelatinous sheath (f) 

58 

surrounds the flagellated (g) cells. The chloroplast (h) 

contains an eyespot (i). 

Cladophora 

This alga has branched filaments whose cells contain 

numerous pyrenoids (j) in reticulate chloroplasts (k). 

Acetabularia 

This marine alga, known as “mermaid’s wineglass,” is 

one immense cell with a giant nucleus (l) in the basal 

rhizoid (m). The nucleus migrates to the cap (n) where 

reproductive cysts are formed. 

Scenedesmus 

This is a coenobium composed of four cells that are 

joined laterally. The laminate chloroplast (o) contains a 

pyrenoid (p). There is one nucleus (q) per cell. 

Micrasterias 

The cell wall, enclosed by a gelatinous sheath (r), is divided 

into two halves. Each half of this unicellular alga 

has a chloroplast (s) with pyrenoids (t). The nucleus is 

located at the contraction (isthmus, u) between the cell 

halves. For asexual propagation, the nucleus divides in 

half, the cell splits into two halves and separates. Then 

each half grows a new partner to form a cell as illustrated. 

This plant occurs in freshwater ponds and lakes. 

Spirogyra 

Spirogyra is an unbranched filamentous freshwater 

alga. One cell in a filament is shown. It has two spiral 

chloroplasts (v) with numerous pyrenoids (w). The 

nucleus (x) is suspended in the center by threads of 

cytoplasm. 

COLOR CODE 

colorless: flagellum (a, g), sheath (f, r), rhizoid (m) 

white: pyrenoid (d, j, p, t, w) 

gray: nucleus (e, l, q, u, x) 

red: eyespot (c, e, i) 

green: chloroplast (b, h, k, o, s, v), cap (n)

Brown Algae 

The algae in this division are mainly marine. They 

live along cooler coastal, intertidal areas, forming large 

beds of brown seaweed. Common features among the 

different genera are the pigments of chlorophylls a and 

c, β-carotene, violaxanthin and fucoxanthin, source of 

the brown color; a sugar food reserve (laminarin); and 

cell walls made up of an inner cellulose layer and an 

outer mucilaginous layer. Diverse size ranges from microscopic 

to enormous kelps up to 60 meters in length. 

Of the 250 known genera there are more than 900 

species. 

Asexual reproduction occurs by fragmentation and production 

of sporangia with zoospores. When a section 

of a living filament breaks off, the fragment becomes a 

new individual. A sporophyte individual produces sporangia 

with zoospores, that when released, develop into 

more sporophyte individuals. 

Sexual reproduction is by sex cells (gametes) that 

look alike (isogamy), or are unlike (anisogamy), 

or by formation of motile sperm with a stationary 

egg (oogamy). 

Of interest . . . ecosystem: dense beds of kelp along 

sea coasts provide a substrate for small animals, protection, 

and foods for swimming animals and fish, and 

they contribute to phytoplankton communities; industry: 

algin (a cell wall constituent) contains sodium, ammonium 

and potassium salts (these salt compounds 

are used in fireproofing fabrics, as laundry starch substitutes, 

as ice cream stabilizers, as binders in printer’s 

ink, in soaps and shampoos, in photographic film coatings, 

in paints and varnishes, and in leather finishes; 

insecticides; toothpaste, shaving cream, and lipstick); 

fertilizer: brown algal organisms contain more potassium, 

less phosphorus, and about the same proportion 

59 

of nitrogen as animal manure; food: species of kelps 

are used as food (lombu) in Japan. 

Ectocarpales. Of the 13 orders, the most primitive 

brown algae are found in this order. The body (thallus) 

consists of erect filaments of a single row of cells (uniseriate) 

with basal branching systems (heterotrichy). 

Their size ranges from microscopic to forms up to 

25 cm. long. 

Ectocarpus 

This alga is found on most seashores growing upon 

other plants (epiphytic). The filaments (a, b) of the alga 

have a filmy appearance. The cells have net-like (reticulate) 

chlorophasts (c). Alternate generations are represented 

by sporophytes and male and female gametophytes. 

A sporophyte is an individual that produces 

sporangia with 2n spores, while a gametophyte produces 

1n gametes (sex cells). 

The sporophyte produces two types of reproductive 

structures: (1) a muticellular (plurilocular) sporangium 

(d) produces 2n zoospores that germinate into another 

sporophyte plant; (2) a unicellular (unilocular) sporangium 

(e) produces 1n zoospores that germinate into 

gametophytes. Gametophytes develop plurilocular gametangia 

(f) that produce motile gametes of the same 

sex as that of the parent. Fusion of male and female 

gametes results in development of a 2n (diploid) sporophyte. 

If a gamete does not fuse with another gamete, it may be 

by parthenogenic germination produce a 1n (haploid) 

sporophyte. Parthenogenesis is the development of a 

new individual from an unfertilized egg. There are also 

other more complicated variations in the life cycle of 

Ectocarpus. 

COLOR CODE 

tan-green: sporophyte (a), filament (b), chloroplasts 

(c) 

tan: sporangium (d, e), gametangium (f)

Brown Algae (continued) 

Laminariales (Kelps). This order consists of the kelps, 

the largest of all algae. Some reach 100 meters or more 

in length. The microscopic gametophytes have male 

and female gametes on separate individuals. The characteristic 

tissue of the sporophyte is composed of randomly 

arranged cells (parenchyma, for photosynthesis 

and food storage), rather than a continuous filament of 

cells. 

Well-developed meristems generate new cells that contribute 

to growth of the sporophyte thallus in length and 

width. (Meristems are areas of undifferentiated cells 

that can develop into specialized tissues and organs.) 

The macroscopic sporophyte structure consists of a 

blade, stalk (stipe), and holdfast part that is attached 

to the rocky substrate. 

Laminaria 

Most species in this genus have perennial basal structures 

consisting of a stipe (a) and a root-like holdfast (b). 

There is a loss, but later replacement, of the sporopyte 

blade (c) from the stipe’s meristematic region. 

The reproductive structures of the sporophyte are 

asexual unilocular sporangia (d) containing zoospores 

(e). Between the sporangia are thread-like structures 

termed paraphyses (f), with distended tips that provide 

protection for the zoospores. 

Nereocystis leutkeana Ribbon Kelp 

This annual kelp has blades that develop in the same 

manner as Laminaria. Due to progressive splitting, the 

blade (g) appears ribbon-like. The top of the stipe (h) 

bloats into a gas-filled pneumatocyst (i), which serves 

as a float to maintain the buoyancy of the blades at the 

water’s surface as the stipe elongates. 

Sexual reproduction is oogamous as follows: the microscopic 

male gametophyte produces clusters of antheridia 

(k) containing biflagellated sperm at the filament 

tips. The microscopic female gametophyte produces 

a non-motile egg in the oogonium (l). After fertilization, 

a zygote is formed which emerges from the 

oogonium and begins sporophyte development (m). (A 

zygote is the product of fertilization and is potentially a 

new individual.) 

60 

COLOR CODE 

tan-green: stipe (a), blade (c) 

tan: holdfast (b), sporangium (d), 

zoospores (e), antheridium (k) 

white: paraphysis (f) 

yellow-brown: blade (g), stipe (h), pneumatocyst (i), 

sporophyte (m) 

brown: holdfast (j) 

transparent: empty oogonium (l)

Brown Algae (continued) 

Fucales. The algae in this order are unique in that the 

gametophyte generation has been suppressed. Thus, 

there is only a 2n (diploid) organism. It has oogamous 

sexual reproduction by 1n (haploid) gametes (see below), 

which arise by meiosis. Meiosis is a process of 

sexual reproduction in which a 2n (diploid) organism 

produces 1n (haploid) sex cells (gametes) by reduction 

division from one 2n cell to form four 1n cells. 

Fucus vesiculosus 

The thallus of this alga consists of a holdfast, stipe (a), 

and flat, bilaterally branched blades (b) with midrib (c) 

and paired air bladders (pneumatocysts, d). The separate 

male and female plants have swollen fertile areas 

on the blade tips called receptacles (e). They produce 

either male or female conceptacles (f). 

A conceptacle has a pore (g) that opens from the 

surface of the receptacle to surrounding water. Also 

present in the conceptacle are sterile, hair-like threads 

called paraphyses (h), and either oogonia (i) that produce 

eggs, or antheridia (j), that produce biflagellated 

sperm. When eggs are released from the oogonium 

into the water, they produce fucoserraten, asexattractant 

(pheromone), that causes the sperm to swarm 

around them. Fertilized eggs develop into 2n (diploid) 

individuals. 

61 

COLOR CODE 

brown-red: stipe (a), blade (b, c) 

tan: air bladders (d) 

brown: receptacle (e), oogonium (i), 

antheridium (j) 

colorless: conceptacle wall (f), paraphysis (h)

Stoneworts 

According to the fossil record, this ancient group of 6 

living genera lies developmentally between the green 

algae and the liverworts and mosses (bryophytes). Fossils 

of stoneworts are found from the late Silurian period, 

over 400 million years ago. Stoneworts grow submerged 

in fresh water or sometimes in brackish (salty) 

water with rhizoidal attachment to the substrate of either 

soil or rock. With a preference for hard water (high pH), 

stoneworts have incrustations of calcium carbonate that 

account for the “stonewort” name. An obnoxious odor 

is characteristic of the plants. 

Stoneworts grow continuously by means of a single 

dome-shaped apical cell that cuts off by mitotic divisions 

new node and internodal cells. 

Their pigments are chlorophylls a and b, carotenes, and 

xanthophylls. Sexual reproduction is oogamous, which 

means a motile sperm unites with a larger, stationary 

egg. 

Chara Stonewort 

The base of this plant, the protonema (a), has 

substrate-anchoring rhizoids (b), while the upper portion 

of the stem (c) has whorls of branches (d) at the 

nodes. The stem is a long axis of cells divided into 

small regions (nodes and internodes). The node divides 

producing whorls of branches. The internode is made 

up of one cell containing a single nucleus. The repro- 

62 

ductive structures, male globules and female nucules 

(e), arise at nodes on the branches. 

The male globule (antheridium) has an outer layer of 

sterile shield cells (f). Small cells (g) arise on the inner 

surface which produce antheridial filaments (h). Each 

cell in the filament produces a single sperm with two 

flagella for motility. The shield cells break open, permitting 

sperm cells to swim free. 

The female nucule (oogonium) is attached to a node 

by a short stalk-like cell (i). Sterile sheath cells (j) spiral 

around the single egg (k). At the top are small coronal 

cells (l). At maturity, slits that form under the coronal 

cells allow the sperm to enter the oogonium. 

After fertilization, the sheath cells thicken around the zygote 

(oospore), which overwinters as a dormant structure. 

After germination in the spring, the zygote wall 

splits and the primary protonema (m) emerges to form 

a new sporophyte plant. 

Of interest . . . gravisensors: barium sulfate crystals in 

the tips of the rhizoids sediment in the gravitational field, 

thus enabling the rhizoids to respond to gravity and 

bend downward towards the substratum (starch-filled 

amyloplasts in root caps of higher plants serve the same 

function). The large cells of stoneworts have proven to 

be highly suitable for experimental study of patterns 

of cell growth, orientation of cell wall microfibrils, transport 

of ions into and out of the cells, and cytoplasmic 

streaming (cyclosis). 

COLOR CODE 

gray-green: protonema (a, m), stem internode (c), 

branches (d) 

white: rhizoid (b) 

red: nucules (e), sheath cells (j) 

tan: egg (k), coronal cells (l) 

colorless: shield cells (f), filaments (h) 

red-brown: cells (g) 

green: stalk cell (i)

Liverworts, Hornworts, Mosses 

This most primitive group of green land plants are called 

bryophytes. Mostly perennials, the plants are small in 

size and have no vascular tissues. Humid habitats provide 

a water medium for the motile (flagellated) sperm 

to reach the egg. Bryophytes cannot tolerate salt water, 

excessive heat, or pollution. Mosses can dry down 

during drought, then recover with rainfall. They are also 

tolerant of freezing. Liverworts, on the other hand, cannot 

tolerate dryness, but can survive freezing. 

Bryophytes have two generations. The dominant plant 

(gametophyte generation) develops from a 1n (haploid) 

spore and produces sperms and eggs. A fertilized egg 

forms a 2n zygote, which develops into the sporophyte. 

The smaller sporophyte generation produces 1n spores 

by meiosis that are dispersed and develop into gametophytes. 

In some bryophytes, asexual structures called 

gemmae cups (a) contain gemmae (b) that develop 

into gametophytes. 

Liverworts (Hepaticae). The liverworts are primitive 

bryophytes. The gametophyte is flat and strap-shaped, 

as in Marchantia, or leafy as in Bazzania. The gametophyte 

body (thallus, c) branches equally (dichotomously). 

Marchantia polymorpha 

This species has unisexual thalli (dioecious). The male 

gametophyte develops antheridia-bearing stalks (antheridiophores, 

d), which produce motile sperm in 

its disc-shaped top. The female gametophyte develops 

an archegoniophore (e), which produces archegonia, 

flask-shaped structures containing eggs, under its 

umbrella-shaped top. After fertilization, a 2n zygote develops 

into a sporophyte, which in turn produces spores 

that develop into gametophytes. 

Hornworts (Anthocerotae) 

Anthoceros punctata Common Hornwort 

The gametophyte thallus (f) forms a flat rosette. Male 

and female structures occur in the upper layers of the 

thallus. The union of sperm and egg produces the 

sporophyte. A foot (g) secures the sporophyte (h), to 

the gametophyte thallus. The sporophyte splits at the 

top into 2 valves to expose the spores. 

Mosses (Musci). All moss gametophytes have 3- to 

5-ranked leaves. Most mosses develop from a spore 

63 

into a thread-like structure (protenema) with rhizoids, 

then into a leafy gametophyte. The young sporophyte 

is green and photosynthetic. Its firm tissue eventually 

turns brown and may persist on the gametophyte for 

years. Unlike the liverworts and hornworts, mosses 

show a great deal of variation in gametophytes and 

sporophytes. Mosses form large colonies by fragmentation 

and gemmae. 

Sphagnum centrale Peat Moss 

The peat mosses (Sphagnum, i) grow in acid bogs. They 

secrete hydrogen ions, contributing to the acidity. This 

acid environment delays the vegetation decay process. 

Thus, sphagnum mosses contribute to mat formation 

at the open water margin of the bog. This provides a 

habitat for other types of plants. Undisturbed, a bog 

can eventually develop into a forest through the process 

of succession. Due to its great water-holding capacity 

Sphagnum peat, derived from old bogs, is added to 

garden soil to acidify it and hold moisture. 

Andrea rupestris Rock-loving Moss 

This plant is found mainly on rocky outcroppings. The 

leafy gametophyte (j) is branched. The sporophyte is 

raised on a stalk (pseudopodium, k). When the capsule 

(l) dries the inner walls contract into 4 slits, releasing 

the spores. 

Tetraphis pellucida Four-tooth Moss 

Moist rotting logs in coniferous forests provide the 

main habitat for this plant. Leafy gametophytes (m), 

attached by rhizoids (n), produce gemmae cups (o). 

The sporophyte is borne on a long stalk (seta, p), 

that twists near the capsule (q). A pleated covering 

(calyptra, r) protects the capsule; it falls off at maturity. 

A lid (operculum) opens to expose 4 teeth (peristome, 

s). When wind or animals shake the capsules, spores 

are released. 

COLOR CODE 

green: gemma cups (a, o), gemmae (b), thallus 

(c,j,m) 

tan: antheridiophore (d), archegoniophore 

(e), foot (g), pseudopodium (k), capsule 

(l, q), seta (p), calptra (r), teeth (s) 

black: sporophyte (h) 

gray-green: thallus (i) 

white: rhizoids (n)

Whisk Ferns 

The whisk ferns are believed to be among the most 

ancient of living vascular plants. There is no known 

fossil record to determine relationships with extinct 

forms. There are two psilophyte genera: Psilotum and 

Tmesipteris. 

Characteristics. These are rootless, simple plants 

with rhizoids, as anchoring structures, and hairless 

(glabrous) upright stems with simple sterile appendages 

(enations). The large spore cases (sporangia) 

are fused into two’s or three’s. 

Reproduction. In whisk ferns, an alternation of generations 

results in a dominant sporophyte plant producing 

alike spores (homosporous), which germinate to form 

1n (haploid) gametophytes. The underground gametophyte, 

which forms mycorrhizal associations with fungi 

for nutrition, develops archegonia, each with 1 egg, and 

antheridia with flagellated sperm. 

After fertilization, a 2n (dipoid) zygote forms, which 

eventually develops into a sporophyte plant. Asexual reproductive 

bodies (gemmae) may be produced on the 

sporophyte. 

Of interest . . . Whisk ferns are dominant components of 

the tropical ecosystems of Hawaii’s island archipelago. 

In fact, they are considered to be weeds in Hawaii due 

to their propensity to colonize disturbed areas, (W. H. 

Wagner, Jr., personal communication). 

Psilotum nudum Whisk Fern 

This plant may be terrestrial or grow upon other plants 

(epiphytic) in the tropics and subtropics. The shoot is 

upright with stems (a) that branch into two equal parts 

(dichotomous branching). Simple leaf-like appendages, 

called enations (b), emerge from the stem. The threelobed 

spore case (c) has a small, forked, leaf-like scale 

(d) below. 

Tmsipteris tannensis var. lanceolata 

This plant is found only in the southwestern Pacific 

Ocean area. It has a simple stem (e) with flat, singleveined, 

leaf-like appendages (f). The sporangium (g) is 

two-lobed. 

64 

COLOR CODE 

light green: stem (a), enations (b), scale (d) 

yellow: sporangium (c) 

green: stem (e), enations (f) 

tan: sporangium (g)

Clubmosses, Spikemosses, 

Quillworts 

This distinct group of ancient plants has five living 

genera. Common features are single-veined leafy appendages 

(microphylls), two-part branching which 

may be equal or unequal, axillary sporecases (sporangia), 

and flagellated sperm. 

Clubmosses (Lycopodiales). Lycopodium, with 700 

species, is found worldwide, with most species occuring 

in the tropics. Plants are herbaceous, perennial, 

and usually evergreen. No leaf outgrowths (liguIes) 

are present. Some species bear sporangia in terminal 

spikes (strobili). 

Lycopodium annotinum Stiff Clubmoss 

The creeping horizontal stem (rhizome) of this plant has 

upright shoots with annual constrictions (a). The spirally 

arranged leaves (b) are narrow and spread in different 

directions. In the alternation of generations, the 

spore germinates into a plant (gametophyte) bearing 

male and female sex cells (gametes). Then, after fertilization, 

an embryo develops into a sporophyte, the 

dominant plant. 

A “cone” (strobilus, c) of specialized leaves (sporophylls), 

bearing sporangia in the axils, terminates an 

upright shoot. The sporangia contain one type of spore 

(homosporous). 

Spikemosses (Selaginellales). Selaginella, the single 

genus, has about 600 species. Differing from 

Lycopodium, there are ligules, root-like organs 

(rhizophores) occurring at dichotomies, and sporangia 

always in a “cone,” bearing spores of two sizes 

(heterosporous). Reproduction is the same as shown 

below for Isoetes. 

While most species prefer moist conditions, there is 

an unusual species, Selaginella lepidophylla which is 

called resurrection plant. It is native to dry regions of 

the southwestern United States and Mexico. Dry specimens 

of this plant are occasionally found in plant stores 

as a curiousity because it appears as a dried leafy mass 

until “revived” with water that causes it to turn green 

and flatten into a rosette. It can be dried and revived 

repeatedly. 

65 

Selaginella rupestris Rock Spikemoss 

The creeping stem has spirally arranged leaves (d), 

root-like appendages (rhizophores, e), and 4-sided fertile 

spikes (f). 

Quillworts (Isoetales). These plants are considered 

by some botanists to be the last remnant of the fossil 

tree lycopods due to their peculiar secondary growth, 

heterospory and presence of ligules. Isoetes, with 60 

species, grows mostly submerged in lakes, ponds, and 

streams. 

Isoetes echinospora Braun’s Quillwort 

The sporophyte has an enlarged perennial underground 

stem, the corm (g). The roots (h) branch dichotomously, 

and annual strap-shaped leaves (i) grow 

in a spiral cluster (rosette). The leaf has a ligule (j), 4 

vertical air chambers (k), and an expanded fertile base 

covered by a flap (velum, l). 

At the bases heterosporous leaves (mega- and microsporophylls) 

bear megasporangia (m) containing 

large spores (megaspores, n) or microsporangia (o) 

with small spores (microspores). The megaspore wall 

is variously ornamented according to species. The 

megaspores develop into female gametophytes, while 

the microspores produce male gametophytes. 

Stylites andicola Andes Quillwort 

This plant, forming cushions in marshes, was discovered 

in the Andes Mountains of Peru in 1957. The stem 

(p) branches dichotomously with the leaves (q) atop 

each section. The roots (r) develop on the sides of the 

stem. 

COLOR CODE 

dark green: leaves (b) 

green: spike (c), leaves (d, q), ligule (j) 

white: rhizophores (e), roots (h, r), 

megasporangium (m), 

microsporangium (o) 

tan: velum (l), stem (p) 

light green: spike (f), leaves (i) 

brown: corm (g) 

yellow: megaspore (n)

Horsetails 

The single genus, Equisetum, with 15 species, is the 

only present-day member of plants in this family, Equisetaceae. 

It is related to the fossil plant, Calamites (see 

43). Species of Equisetum are found worldwide except 

in Australia and New Zealand. 

Characteristics. These annual or perennial terrestrial 

plants are less than 1 meter in height, with the exception 

of the Costa Rican tropical E. giganteum, which grows 

to 8 meters in height. The plant consists of a jointed underground 

perennial rhizome and annual upright jointed 

shoots. 

Species with branched shoots are commonly called 

“horsetails” and unbranched species are known as 

“scouring rushes” because of their earlier use as pot 

scrubbers (effective because of the presence of amorphous 

silica, SiO2·nH2O, in the stem surface). 

The photosynthetic stem is round and grooved on the 

outside and hollow in the center. At the stem node is 

a sheath of greatly reduced leaves of various teethlike 

shapes, depending on the species. In branched 

species, whorls of branches develop at the base of 

the leaf sheath. Internodes of the rhizomes and aerial 

shoots elongate by means of basally localized intercalary 

meristems (see 15). 

Reproduction. The plant has an alternation of a sporophyte 

generation with an either male or bisexual gametophyte 

generation as follows: The sporophyte produces 

a terminal “cone” (strobilus) with whorls of 

hexagonal scales (sporophylls) on stalks. Attached to 

each scale are 5 to 10 spore-bearing sacs (sporangia) 

containing alike spores (homosporous). The spores 

contain chlorophyll. They germinate within a few days, 

developing into tiny green thalloid gametophytes that 

produce antheridia with sperm or both antheridia and 

archegonia. Fertilization of the egg in an archegonium 

66 

by a sperm results in a zygote that develops into a new 

sporophyte plant. 

Equisetum variegatum Variegated Scouring 

Rush 

Equisetum stems (a) are grooved and possess hollow 

air channels within. The air channels include a central 

canal (b), carinal canals (c), and vallecular canals (d) 

at the bottom of each groove. Size and shape of the air 

canals vary with species. 

Equisetum arvense Field Horsetail 

This species has two forms (dimorphic). In the spring, 

an unbranched fertile shoot (e) emerges from the rhizome 

(f). It is short-lived and dies back when the spores 

are shed from the strobilus (g). The other form of 

stem (h) is smooth and branched (i). By summer, the 

branches have elongated. The leaf sheaths (j) in this 

species have dark, lance-shaped teeth (k). 

Equisetum laevigatum Smooth Scouring Rush 

The scouring rush stem (l) is unbranched. The leaf 

sheath (m) is flared and has deciduous teeth (n). The 

strobilus (o) shows the hexagonal surface of the sporophylls 

(p). 

Equisetum hyemale Common Scouring Rush 

A sporophyll removed from the stobilus exposes the 

sporangia (q) containing the spores. 

Equisetum scirpoides Dwarf Scouring Rush 

A spore (r) surface splits into 4 strips of water-absorbing 

(hydroscopic) elators (s). When dry, the elators (t) expand 

and aid in spore dispersal. 

COLOR CODE 

green: stem (a, h), branches (i), sheath (j), 

sporangium (q) 

colorless: canals (b, c, d) 

tan: shoot (e), strobilus (g) 

dark brown: rhizome (f) 

yellow-green: stem (l), sheath (m), surface of 

sporophylls (p), spores (r), elators (s, t)

Ferns 

Characteristics. Although fern origins are uncertain, 

fossils have been found dating back to the Devonian. 

Most fern species have leafy fronds that unroll as the 

leaf expands (circinate development, see 69). Stems 

lack secondary growth, have roots that are usually 

creeping or below ground, and may have protective 

hairs or scales. The leaves may be simple, feather-like 

(pinnate), lobed, with veins arising from one point (palmate), 

or with veins which appear to branch. Plant size 

ranges from a few millimeters to 15 meters. 

Ferns are perennials and may take the form of twining 

vines, floating plants, trees, epiphytes, or, most commonly, 

terrestrial herbs. While most species of ferns 

are found in the moist tropics, some grow in bare rocky 

habitats, or temperate swamps, fields and forests. 

Reproduction. Asexual reproduction occurs by offshoots 

from a rhizome and by spores. The sporophyte 

generation is dominant and produces 1n spores 

in spore cases (sporangia), usually on the lower leaf 

surface. The spore cases are massive in the primitive 

orders, Ophioglossales (Adder’s-tongue Ferns) and 

Marattiales. 

In the more advanced orders, the spore cases are 

minute, nearly microscopic, stalked, and in a “fruit dot” 

cluster called a sorus. The sculptured, thick-walled 

spores are dispersed by wind and germinate into the 

sexual gametophyte generation. The tiny, rarely seen 

gametophyte produces sperm in antheridia and eggs 

in archegonia. For fertilization to take place, the sperm 

must swim in water to the archegonium, a vase-shaped 

structure with one egg. After fertilization, a 2n zygote is 

formed and develops into a sporophyte on the gametophyte. 

The gametophyte then dries up and dies. 

Of interest . . . ornamentals: Adiantum pedatum (maidenhair 

fern), Athyrium filix-femina (lady fern), A. nipponicum 

‘Pictum’ (Japanese painted fern), Asplenium 

nidus (bird’s-nest fern), Camptosorus (walking fern), 

67 

Cyrtomium (holly fern), Dryopteris erythosora (autumn 

fern), D. filix-mas (robust male fern), D. marginalis 

(marginal wood fern) Nephrolepis (Boston fern), Onoclea 

sensibilis (sensitive fern), Osmunda cinnamonea 

(cinnamon fern), O. regalis (royal fern), Platycerium 

(staghorn fern), Polystichum acrostichoides (Christmas 

fern), P. polyblepharum (tassel fern); poisonous: 

Pteridium (bracken fern); horticulture: Osmunda 

(dried roots used as medium for growing orchids); fertilizer: 

Azolla (mosquito fern, see 70). 

Ophioglossales. Plants in this order are mostly small 

and succulent with the leaf divided into sterile and 

fertile, sporangial-bearing parts. There are four genera: 

Botrychium (grape ferns), Ophioglossum (adder’stongue 

ferns), Cheiroglossa, and Helminthostachys. 

Botrychium dissectum Dissected Grape Fern 

The single succulent compound leaf (a) is divided into 

pinnae (b), a primary subdivision of the leaf and pinnules 

(c), a further subdivision of the pinnae. The fertile 

stalk (d) is divided into many branches where sporangia 

(e) are borne in grape-like clusters. The roots (f) are 

coarse. This terrestrial fern is found on the forest floor 

of woods and in swamps. 

Helminthostachys zeylanica 

This fern is found in Southeast Asian and Polynesian 

swamps. The compound leaf is divided into 3 leaflets 

(h). The fertile spike (i) has very short branches bearing 

sporangia (j). 

Ophioglossum vulgatum Adder’s-tongue Fern 

The single stalk (k) has one simple blade (l) without a 

petiole (sessile), and sunken sporangia (m) borne terminally 

in a spike. The roots (n) are smooth and fleshy. 

Adder’s-tongue fern grows in damp areas in fields and 

woods in the temperate region. 

COLOR CODE 

green: leaf (a, b, c, h), stalk (d, g), spike (i) 

orange: sporangia (e, j) 

brown: roots (f) 

light green: stalk (k), leaf (l) 

yellow: sporangia (m) 

white: roots (n)

Common Ferns 

Common Ferns (Polypodiales). Most common ferns 

are in this order. They are usually of medium size among 

the ferns and are found on most parts of the earth. 

Sporangia are single, or more often, there are many 

in a cluster called a sorus. In some genera, the sorus 

has a protective covering (indusium). Some ferns in 

this order produce sporangia on separate, fertile stalks, 

but most have the sporangia on the underside of the 

frond (leaf) in sori, or on the entire surface, or in rows 

along the veins, or under the curled edge of the leaflets. 

There are over 8,000 species. 

Osmunda regalis Royal Fern 

There are three species of Osmunda: O. cinnamomea 

(cinnamon fern), O. claytonia (interrupted fern), and 

O. regalis (royal fern). O. cinnamomea has two types of 

stalks (dimorphic): a sterile frond (leaf) and a separate 

fertile stalk with cinnamon-colored sporangia. It grows 

in shady, wet areas with acid soil. The fertile fronds of 

O. claytonia have a fertile central area of sporangia 

on the stalk with pinnae above and below. It prefers 

a dry type of soil compared to the other two species of 

Osmunda. 

Osmunda regalis is shown here. The fern leaf (a) is 

twice divided into pinnae (b) and bears sporangial 

branches (c) terminally. The round single spore cases 

(sporangia, d) open in halves and occur in clusters (e). 

The deciduous leaves arise from a perennial rhizome 

with black wiry roots. Royal fern grows in very wet habitats 

with acid soil. 

Dryopteris carthusiana (D. spinulosa) 

Toothed Wood Fern 

The usually evergreen leaf of this fern is three-times 

dissected, forming delicate pinnules (f) in the pinna 

(g). Scales (h) cover the petiole (i). Sori are produced 

on the leaf underside. The sorus (j) is covered by a 

kidney-shaped indusium (k) that protects the sporangia 

(l). The preferred habitat is moist shade to partial 

sun. There are about 150 species of Dryopteris (wood 

ferns). 

68 

COLOR CODE 

red-brown: petiole (a), sporangium (d, l), 

sporangial clusters (e) 

green: pinnae (b), pinnules (f) 

tan: scales (h), petiole (i), indusium (k)

Fern Leaf Development 

Common Ferns (continued) 

Rumohra adiantiformis Leatherleaf Fern 

Florists frequently use the sturdy fronds of this tropical 

fern. The young leaf meristem is protected by scales (a, 

b). As in other common ferns, the fiddlehead (crozier, 

c, d) expands by unrolling (circinate development). 

Ferns are the only plants with this type of leaf development. 

As the stalk (petiole) elongates, the blade midrib develops 

leaflets (pinnae, e). In this genus, the leaflets 

(pinnae) are further divided into smaller leaflet sections 

called pinnules (f, g). 

(This illustration was made from a series of drawings 

from one leaf as it developed.) 

69 

COLOR CODE 

brown: scales (a, b) 

green: crozier (c, d) 

dark green: leaf (e, f, g)

Water Ferns 

Water Ferns (Marsileales). Water ferns in this order 

usually have rooted rhizomes. The leaf may have 0, 2, 

or 4 leaflets on a long petiole. Spore-bearing receptacles 

(sporocarps) are formed along the petiole. A 

sporocarp develops both small microspores and larger 

megaspores (a heterosporous condition) on one plant 

(monoecious). 

Marsilea quadrifolia Water Clover 

This pond plant is rooted (a) in mud with leaves floating 

on or near the water surface. The creeping rhizome (b) 

develops new leaves (c), which have 2 pairs of opposite 

leaflets (d). 

Salviniales (Floating Ferns). The floating ferns include 

Salvinia and Azolla. The plant consists of a 

branched stem and leaves. Sporocarps containing two 

types of spores (heterosporous) are borne on the 

leaves. 

Salvinia Water Spangles 

The leaves occur in whorls of 3 with two keeled, green 

floating leaves (f) and a colorless, finely divided, submerged 

leaf (g). The upper surface of the floating leaves 

is covered with rows of 4 rib-topped, transparent hairs 

(h). The hairs cause water droplets to maintain surface 

tension and roll off the leaf surface. 

The submerged leaf filaments are covered with brown 

hairs, which function as roots for water and nutrient absorption. 

Sporocarps (i) are borne on submerged leaf 

filaments. 

Azolla Mosquito Fern 

This floating fern has simple roots (j) that hang down 

in the water. The leaves are alternate on the stem (k) 

and two-lobed, having a green, fleshy lobe (l) above the 

water and a colorless flat lobe (m) on the water surface. 

Some Azolla species have a symbiotic relationship with 

a blue-green, Anabaena (see 44), which lives in cavities 

of the fern. Anabaena converts nitrogen from the air into 

a reduced form (ammonia - NH3) that can be used by the 

fern and surrounding water plants such as rice (Oryza 

sativa). Because the presence of Azolla with Anabaena 

increases rice production, this tiny plant is probably the 

economically most important fern. 

70 

COLOR CODE 

brown: roots (a), leaf hairs (g) 

white: rhizome (b), root (j), stem (k) 

green: leaf (c), leaflets (d), petioles (e) 

light green: leaf (f), leaf lobe (l) 

tan: sporocarps (i)

Cycads 

The fossil history of the cycads extends back 200 million 

years to the Mesozoic era. Cycads are now confined 

to the tropics and subtropics as living relics of once 

worldwide distribution. They are the most primitive living 

seed plants. 

Characteristics. Cycads look like sturdy ferns or palm 

trees. They have thick upright stems with a primary 

thickening meristem and not much secondary growth. 

The leaves are large, compound fronds with leaflets. 

Leaflets are thick and tough, usually with equally 

branching (dichotomous) veins. 

Typically, cycads reach a maximum height of 2 to 3 meters, 

but some species grow to 20 meters high. Cycad 

plants are slow-growing and long-lived, some as old as 

1,000 years. 

Reproduction. Unisexual cones (strobili) are borne 

on separate plants (dioecious). The male cone has 

spirally arranged cone scales (microsporophylls) with 

spore cases (sporangia) on the lower surface. The 

spore case contains microspores that develop into 

pollen grains that are dispersed to the female reproductive 

cones. There, the pollen grain develops mutiflagellated 

sperm. The cycads and Ginkgo are the only 

living seed plants having flagellated sperm. 

The female cone scales (megasporophylls) produce 

ovules in which eggs develop. After fertilization, 

71 

brightly-colored, usually red, seeds are formed. Cycads, 

Ginkgo, conifers and gnetes are referred to as 

gymnosperms, meaning “naked seed, “ because the 

seeds are borne in an exposed position on the sporophyll. 

Of interest . . . houseplants or landscape plants for 

tropical areas include Bowenia serrulata, B. spectabilis, 

Ceatozamia latifolia, C. robusta, Cycas circinalis (fern 

palm), C. revoluta (sago palm), Dioön edule, Encephalartos, 

and Zamia. 

Zamia furfurscea 

Leaflets (a) have dichotomous venation but do not have 

midribs. They leave prominent leaflet scars (b) when 

they are shed (abscise). The male cone (d) has stalked 

cone scales (e) with clusters of spore cases (f) on the 

under surfaces. The female cone scale (g) has a hexagonal 

surface (h), and below, are 2 ovules (j) in which the 

eggs develop. 

Dioön edule 

The habit illustration of this cycad shows the prominent 

stem (l) covered with old leaf bases (m). A spiral pattern 

of leaves (n) emerges at the apex. Leaflets (o) are 

arranged in two rows. 

COLOR CODE 

green: leaflets (a, o) 

tan: leaf stalk (c), spore case (f), cone stalk 

(k), cone scale stalk (i) 

brown: cone (d), cone scale stalk, surface (e) 

dark green: cone scale (g, h) 

white: ovules (j) 

red-brown: stem, leaf (l, m)

Ginkgo 

This division has only one living member: Ginkgo biloba 

(Maidenhair Tree). Fossil records show it probably originated 

in the Permian about 250 million years ago. 

Members of the division were globally distributed, but 

became extinct except for this single species in southeastern 

China. Ginkgo is similar to cycads in reproductive 

structures and gametophyte development, but the 

leaves are distinctively different. The stem, with extensive 

wood, small pith and cortex, and cell wall pitting, is 

similar to that of the conifers (see 15). 

Ginkgo biloba Maidenhair Tree 

This plant was cultivated in temple and monastery gardens 

of China and Japan for centuries. The Chinese 

name was mistransliterated and should be Ginkyo. The 

common name is derived from a resemblance of the 

leaves to the leaflets of the maidenhair fern (Adiantum 

pedatum). 

Characteristics. A hardy tree with a slow maturation 

rate, Ginkgo can grow to 30 to 40 meters (60 to 80 

feet) in height and over 1 meter (3.3 feet) in diameter. It 

can live to 1,000 years. After the first 10 to 20 years of 

vertical growth, laterally spreading branches develop. 

The leaf blades (a) are fan-shaped, lobed, and have 

dichotomous venation (each vein branches into two 

smaller veins). The alternate leaves are mainly twolobed 

(biloba, b) on long shoots (c) and wavy-margined 

on short spur shoots (d) where they appear in a whorled 

72 

arrangement. In autumn, the deciduous leaves fade to 

yellow (chlorophylls disappear) and all are shed from a 

tree within a few hours, especially after a hard frost. 

Reproduction. Unisexual structures are borne on separate 

trees (dioecious). The male structures are catkinlike 

strobili (e) of spore cases that develop in leaf axils. 

Two male spore cases (f) develop on a stalk (g). The 

female strobilus has two terminal, “naked” ovules (h) 

on a stalk (i) and thus, Ginkgo is referred to as a gymnosperm 

(= naked seed). 

In the spring, wind carries pollen to an opening (micropyle) 

in the ovule. The seed (j) has a fleshy outer 

layer with the odor of rancid butter when mature. 

An embryo with two primary leaves (cotyledons) develops 

after the seed has been shed. 

Of interest...this “living fossil” may be the oldest surviving 

seed plant. It is cultivated as an ornamental shade 

tree because of its resistance to pathogens and pollutants, 

and its drought and low-temperature tolerance. 

The tree needs sun, but grows in almost any soil. 

Because of the odoriferous seeds from female trees, 

male trees are preferred. There are various cultivars selected 

for particular shapes. ‘Autumn Gold’ is a broadshaped 

cultivar. The ‘Fairmount’ cultivars are coneshaped. 

‘Sentry’ (Ginkgo biloba cv. fastigata) cultivars 

are narrow, column shaped. 

COLOR CODE 

yellow: long shoot leaf (b), male strobili (e), 

spore cases (f) 

green: leaves (a), stalks (g, i) 

tan: long shoot (c) 

brown: spur shoots (d) 

light green: ovules (h) 

yellow-orange: seed (j)

Conifers 

Conifers have been present on the earth since the Carboniferous. 

Present-day conifers have fossil records 

dating back to the Jurassic time of the Mesozoic. 

Conifers, as well as cycads, Ginkgo and gnetes, are referred 

to as gymnosperms (gymno = naked, sperm = 

seed) because of their naked seeds. There are 550 

species of 50 genera of conifers. 

Characteristics. Almost all conifers are woody trees, 

having one central trunk from which branches extend. 

Most have narrow, evergreen leaves commonly called 

needles (see 21, 22). Leaves are borne singly or in 

fascicles. They may be arranged in a spiral, opposite, 

or whorled manner, or occur on short spur shoots. Larix 

(larch) and Taxodium (bald cypress) have deciduous 

leaves that are shed in autumn. 

Conifers prefer cooler climates forming climax forests 

at high altitudes, as well as in the temperate regions. 

Conifers are the tallest known trees, with giant 

sequoia (Sequoiadendron giganteum) and redwood 

(Sequoia sempervirens), which may reach 115 meters 

and live thousands of years. There are seven families: 

pine family (Pinaceae), araucaria family (Araucariaceae), 

sequoia family (Taxodiaceae), cypress family 

(Cupressaceae), podocarpus family (Podocarpaceae), 

plum-yew family (Cephalotaxaceae) and yew family 

(Taxaceae). 

Reproduction. Conifers bear pollen sacs and ovules 

in separate structures (stobili = cones) on the same 

plant (monoecious). Wind currents carry pollen to female 

strobili, where the naked seeds are borne. Or the 

strobilus may be an open fleshy aril that surrounds a 

single seed, as in Taxus (yew). 

Of interest . . . timber and paper pulp: Abies (fir), 

Chamaecyparis spp. (false-cypress), Picea spp. 

(spruces), Pinus spp. (pines), Pseudotsuga menziesii 

(Douglas fir), Sequoia (redwood), Taxodium (bald 

cypress); naval stores (turpentine, wood oil, wood 

tars, rosin): Picea spp. (spruces), Pinus (pines); food: 

Juniperus (juniper “berry” flavoring), Pinus spp. (seeds 

of pinyon pines); ornamentals: Abies (fir), Araucaria 

araucana/A. imbricata (monkey puzzle tree), A. 

excelsa (Norfolk Island pine), Cupressus (cypress), 

Juniperus spp. (juniper, red cedar), Larix decidua 

(European larch), L. laricina (tamarack, eastern larch), 

L. occidentalis (western larch), Picea spp. (spruces), 

Taxus (yew), Thuga (arborvitae, white cedar), Tsuga 

73 

spp. (hemlocks); poisonous: Taxus (yew: wood, bark, 

leaves, seeds); medicinal: Taxus brevifolia (Pacific 

yew) bark contains taxol, used to treat breast and ovarian 

cancers; Abies balsamina (balsam fir), pitch from 

blister/bubbles on trunks was used to treat burns by 

Ojibwa Indians. It prevents infections, hastens healing, 

and kills the pain; tallest tree on earth: Sequoia sempervirens 

can be up to 25 feet (7.6 meters) in diameter 

and up to 350–375 feet (106.2–113.75 meters) high. 

It is only found in Northern California where 96% of 

virgin redwood forests have been cut down. 

Picea glauca White Spruce 

As a member of the pine family (Pinaceae), this tree 

has needle-like, evergreen leaves (a). The male cone 

is composed of spirally arranged cone scales (b) with 

pollen sacs on the sides. In the spring, after clouds of 

yellow pollen (c) are dispersed, the cone disintegrates. 

The young female cone has woody, spirally arranged 

cone scales (d) with outer bracts (e). On the inner surface 

of each scale, two ovules (f), that after fertilization, 

become embryos that develop into seeds. At maturity, 

the cone (g) opens and winged seeds (h) are released. 

Taxus Yew 

This yew family (Taxaceae) shrub has flat, evergreen 

leaves (i) and bears male and female structures on separate 

plants (dioecious). The female reproductive structure 

has scales (j) at the base, and a band of tissue (k) 

that matures into a fleshy aril (l) that envelops the seed 

(m). The red aril attracts and is eaten by birds that discard 

the poisonous seed. 

COLOR CODE 

green: leaves (a, i) 

red: cone scales (b), aril (l) 

yellow: pollen (c), scales (j) 

tan: cone scale (d), bract (e), ovule (f), 

seed (h) 

brown: cone (g) 

light green: tissue (k) 

brown-green: seed (m)

Gnetes 

There are three genera in this division: Ephedra, Welwitschia, 

and Gnetum. Pollen grains of Ephedra have 

been found from the Permian. Even though origins and 

relationships of these plants with others are not known, 

they are termed gymnosperms because they bear exposed 

ovules. Most Gnetes are dioecious (two households) 

with male and female cones on separate plants. 

Ephedra 

These plants grow in warm, dry temperate areas. They 

are perennial shrubs. Oppositely branching stems (a) 

bear whorls of scale-like evergreen leaves (b) and male 

structures (strobili, c) at the nodes. Sporangia (d) 

are protected by bracts (e) and bracteoles (f). Stalked 

female structures (strobili, g) are borne at nodes and 

protected by bracts (h). Two seeds (i) develop after 

fertilization. 

An alkaloid, ephedrine, occurs in these plants. In ancient 

China, ephedrine was used to relieve hay fever 

and asthma symptoms. Its action stimulates the heart 

and nervous system, by constricting blood vessels and 

expanding bronchial tubes. This raises blood pressure 

and can cause heart attack, tachycardia, palpitation, 

psychosis and death. 

74 

Welwitschia mirabilis 

This unusual plant, discovered in 1859 by Friedrich 

Welwitsch, is native to a small area on the dry, southwest 

coast of Africa. Plants may live for over 2,000 

years. Its woody stem (j) protrudes slightly out of the 

sandy soil and has only 2 strap-shaped leaves (k) produced 

from long-lived intercalary meristems (l). 

Unisexual cones, borne on stalks that arise from the 

apical meristemic region (see 15), are produced on separate 

plants (dioecious). The male cone is composed 

of bracts (cone scales) with bracteoles (m) covering 

a smaller strobilus on each bract. With the bracteoles 

removed, six spore cases (sporangia, n), with three 

lobes each, may be seen. They surround a central, 

sterile ovule (o). Pollen is formed in the sporangia. The 

four-sided female cone has overlapping scales (p). An 

integument (q), consisting of an outer layer of cells that 

covers the ovule, protrudes from each scale. 

Gnetum 

A plant of the tropics, most species are vines (lianas) 

with a few shrubs and trees. Opposite leaves (r) resemble 

those of dicot flowering plants. Unisexual strobili are 

produced on separate plants (dioecious). 

COLOR CODE 

green: stems (a), leaves (b, r), stobilus (c, g), 

bracts (e, h), bracteoles (f) 

yellow: sporangia (d,) 

tan: seeds (i), stem (j), bracteoles (m), 

ovule (o), scales (p) 

light green: apical meristem (l) 

gray-green: leaves (k)

Flowering Plant Classification 

The dominant plants of the earth today are the flowering 

plants. While their fossil record dates from the 

Cretaceous when they diversified rapidly, their ancestral 

origin is not known (see 41). Sizes range from a 

one-millimeter duckweed (Wolffia) to the 100-meter tall 

Australian gum tree (Eucalpytus). 

Flowering plants are called angiosperms (angio = covered, 

sperm = seed), plants that have seeds enclosed 

in a fruit that develops from an ovary. There are two 

classes: Magnoliopsida, the dicots (embryos with two 

seed leaves—dicotyledons), and Liliopsida, the monocots 

(embryos with one seed leaf - monocotyledons). 

There are 354 families in the two classes. Flower characteristics 

and differences in chloroplast DNA separate 

subclasses and families. 

Dicot (Magnoiliopsida) Subclasses 

Magnoliidae (36 families). These flowering plants are 

among the most primitive. Their flowers usually have an 

indefinite number of parts with many petals, many stamens, 

and many separate carpels. Pollen grains have 

one pore (called unicolpate condition, see 31). 

Hamamelidae (23 families). The flowers are small, 

usually unisexual, and are adapted towards wind 

pollination. 

Caryophyllidae (14 families). This group alone has 

the water-soluble betalain pigments (see 4) of betacyanins 

(beet red-purple) and betaxanthins (yellow, orange, 

orange-red). The flower ovary usually has freecentral 

to basal placentation (see 28) and the ovule integuments 

are twisted and bent. 

Dilleniidae (69 families). The flower has many stamens, 

which mature in a sequence from inside to the 

outside. Parietal placentation of the ovules is common. 

Rosidae (108 families). Structurally, this group has no 

one common feature, but developmentally, the plants 

are placed between the primitive Magnoliidae and the 

advanced Asteridae. 

Asteridae (43 families). In 70% of these plants, the 

flower petals are fused, at least at the base, and the 

stamens arise form the petals. 

Monocot (Liliopsida) Subclasses 

Alismatidae (14 families). These primitive monocots 

are mostly aquatic plants. The flower carpels are 

75 

usually separate and the pollen grains possess three 

pores (tricolpate condition, see 31). 

Commelinidae (16 families). Plants in this subclass 

are mostly terrestrial. The flower carpels are usually 

joined and the seed usually has a starchy endosperm 

(see 40). The sepals and petals are separate or reduced 

to bristles or absent. 

Zingiberidae (9 families). This subclass is separated 

from Commelinidae by the presence of septal nectaries, 

and vessels (see 8) are found only in the roots. 

Arecidae (5 families). The flower are usually small 

and numerous in a cluster, subtended by a bract 

(spathe), and often aggregated into a fleshy spike 

(spadix). 

Liliidae (17 families). Tepals (sepals and petals that 

look alike) and well-developed nectaries are usually 

present in the flower. This subclass includes the most 

specialized monocot flowers. 

Evolutionary Floral Trends 

Evolutionary changes from primitive to more advanced 

forms may include the following. Reduction, where 

flower structures are less in size, number, and kinds 

of parts. Petals are most frequently lost; stamens or 

carpels may be lost (bisexual to unisexual flower, see 

28), with, usually, sepals the last to be lost because 

they protect the young flower. There may be fusion of 

parts, such as petals forming a tube instead of being 

separate. Instead of a superior position, the ovary is in 

an inferior position (see 28). The lower, less-exposed 

position provides more protection of the ovules. The 

shift from insect to wind pollination is regarded as an 

advanced evolutionary change. A change from radial to 

bilateral symmetry is an adaptation for specific insect 

pollinators. In radial (actinomorphic) symmetry, similar 

parts are regularly arranged around a central axis. 

With bilateral (zygomorphic symmetry), flowers can be 

divided into equal halves in one plane only. Some advanced 

flowers are irregular (asymmetrical), incapable 

of being divided into equal halves in any plane. False 

flowers (pseudanthia) are composed of a head (capitulum) 

of small flowers that look like one flower. In the 

center of the head are fertile flowers surrounded on the 

outside by petaloid structures or large-petalled sterile 

flowers.

COLOR CODE 

green: bract (a, h, r), leaf (e), female catkin (g), 

sepals (i, k, o) 

white: perianth (b), spadix of flowers (u), 

male-female column (w) 

yellow: stamens (c, m, q) 

light green: pistils (d, n), ovary (t) 

pink: petals (p, y), sepals (x) 

tan: male catkin (f) 

red: petals (j), bract (v) 

purple: petals (I) 

orange: petal (s) 

dark pink: lip petal (z)

Major Land Plant Communities 

Biomes are characterized by their natural vegetation of 

dominant plants determined by climate and position of 

the continents. In earth’s history, biomes changed as 

the climate cycles cooled or warmed and continents 

drifted. 

Arctic Tundra (a). This biome is wet, arctic grassland 

that supports lichens, grasses, sedges, and dwarf 

woody plants and is cold most of the year. Below 

a few centimeters, the soil is permanently frozen 

(permafrost). 

Northern Conifer Forests (b). Other names are boreal 

forest, spruce-fir forest and taiga. Low temperatures 

prevail for at least half the year. The plants include 

spruces, firs, and pines. 

Temperate Deciduous and Rain Forests (c). In the 

Temperate Zone, deciduous plants have an even distribution 

of 30 to 60 in. (76 to 152 cm) of rainfall annually 

and moderate seasonal temperatures. Redwoods, 

Douglas fir, western hemlock and western red cedar 

(see 73) dominate temperate rain forests along the 

West Coast of the United States. Rain forests of the 

subtropics with high moisture and even temperatures 

have broad-leaved evergreens. 

Temperate Grassland (d). These areas have a low 

annual rainfall of 10 to 30 in. (25 to 76 cm) which effectively 

prevents forest formation. Temperatures range 

from very cold winters to very hot summers. 

Tropical Savanna (e). Warm regions with 40 to 60 in. 

(102 to 152 cm) of rainfall and with a prolonged dry 

season have drought- and fire-resistant grasses with 

scattered trees. 

Desert (f). With less than 10 in. (25 cm) of annual rainfall 

in desert regions, plants include rain-season annuals, 

succulents, and shrubs which can remain dormant 

for long periods. Plants have light-reflecting surfaces 

created by white hairs or waxy cuticle. Small stomata 

(see 10) are sunken or closed much of the time, opening 

at night. They also have extensive root systems. 

Chaparral (g). A mild climate with abundant winter 

rains and dry summers supports a community of trees 

or shrubs with thick evergreen leaves. Fire is an important 

maintenance factor. Native plants are fire-adapted. 

76 

Tropical Rain Forest (h). Equatorial lowlands have 80 

to 90 in. (203 to 230 cm) of annual rainfall. Broadleaved 

angiosperms with evergreen leaves include 

trees, vines, and epiphytes. Without freezing temperatures, 

there are no deciduous-leafed plants. Photosynthesis 

is continuous throughout the year. 

Tropical Scrub (i) and Deciduous (j) Forests. These 

are areas without an even distribution of rainfall. They 

are composed of thorn forests of distorted, small hardwood 

trees. 

Mountains (k). Many irregular bands of different types 

of plant communities are present. Alpine tundra is 

above the treeline (too high for trees to survive). It 

occurs in mountainous areas much south of the arctic 

tundra. Coniferous forest in temperate zones, such 

as the Appalachian Mountain region in Eastern United 

States, has dominant spruces, pines, firs and tamarack. 

Highland rain forests in the tropics can support trees. 

Of interest...Forests of the earth absorb carbon dioxide 

and release oxygen during photosynthesis (see 24). 

As forests are cut down and burned, potential oxygen is 

lost and carbon dioxide stored in the trees is released 

into the atmosphere. The rise of atmospheric carbon 

dioxide causes a rise in temperature. Along with gasemitting 

power plants, automobiles and factories, the 

temperature rose 1 ◦ Fahrenheit during the last century. 

As temperatures continue to rise, land habitats disappear. 

Satellite imaging can monitor deforestation. Brazil 

and Central Africa have the largest tropical rain forests, 

although deforestation by logging and mining is destroying 

this biome. From 1978 to 1996 burning (“slash and 

burn”) and logging to create pastures for livestock and 

fields for agriculture destroyed 12.5% of the Amazon’s 

rain forest. Destruction continues unabated. 

COLOR CODE 

tan: tundra (a) 

dark green: northern conifer forest (b) 

red: temperate deciduous and rain forest (c) 

yellow: grassland (d) 

light green: tropical savanna (e) 

orange: desert (f) 

pink: chaparral (g) 

purple: tropical rain forest (h) 

brown: tropical scrub forest (i) 

gray: tropical deciduous forest (j) 

blue: mountains (k)

Magnolia Family (Magnoliaceae) 

This family of plants is considered to be among the most 

primitive of the flowering plants. It consists of woody 

shrubs and trees that may have deciduous or evergreen 

leaves. The flower parts (sepals, petals, stamens, pistils) 

are spirally arranged and usually without a definite 

number. These are considered to be primitive characteristics. 

There are 12 genera and over 200 species. 

The alternate leaves are simple and usually have 

smooth (entire) margins. They are pinnately (featherlike) 

veined. Petioles are present. Stipules (see 23) enclose 

young leaf buds and are shed as the leaves expand. 

Bracts that enclose flower buds are shed as the 

flower opens. Flowers are often large, showy, and solitary. 

These features attract pollinators, usually primitive 

insects, such as beetles. 

Flowers are usually bisexual, having both male and female 

structures. Sepals and petals look alike or there 

may be 3 sepals and 6 to many petals. Many stamens 

are spirally arranged around a raised axis with 

many pistils. Again, these are considered to be primitive 

characteristics. 

Each pistil has an ovary of one carpel containing one 

to many ovules in parietal placentation (see 28) and 

one style and stigma. Fruit types in this family include 

follicles (as in Magnolia), samaras (as in Liriodendron) 

and berries. 

Of interest...lumber: Liriodendron tulipifera (tulip 

tree, yellow poplar); cabinet work: Magnolia spp. 

77 

(magnolias); ornamentals: Liriodendron tulipifera 

(tulip tree), Magnolia acuminata (cucumber tree), M. 

denudata (Yulan magnolia), M. grandiflora (bull-bay), 

M. stellata (star magnolia), M. tripetala (umbrella tree), 

M. virginiana (sweet-bay), M. × soulangeana (saucer 

magnolia, a hybrid between M. denudata and M. liliflora, 

has large, deep pink, sterile flowers), Michelia fuscata 

(banana shrub), Talauma, Illicium vernum (Chinese 

anise, star anise). 

Magnolia spp. Magnolia 

The illustrations represent three showy ornamental 

Magnolia species: M. xsoulangeana (saucer magnolia), 

M. stellata (star magnolia), and M. grandiflora (bullbay, 

southern magnolia). 

In the spring, magnolia flowers open before the leaves 

(a) expand. Bud coverings of leaf stipules (b) and flower 

bracts (c) are fuzzy with hairs (pubescence). 

The star magnolia flower has many similar appearing 

sepals and petals (e) and many stamens (f) with anthers 

(g) that open longitudinally on both sides. Pistils 

(h) are arranged spirally on a central axis and occur in 

a position superior to other flower parts. Each pistil has 

a style (i) extending from the ovary (j). 

In fruit, the pistils form a cone-like aggregate of follicles. 

A follicle (k) splits along one seam. Inside each are one 

or two, bright red, flesh-covered seeds (l) attached by 

thin strands (called funiculi, m) to the ovary wall (n). 

COLOR CODE 

green: leaf (a), pistils (h) 

gray-green: leaf bud stipules (b), flower bracts (c) 

brown: stem (d) 

white: sepals and petals (e) 

light yellow: stamens (f), anthers (g) 

pale green: style (i), ovary (j) 

pink-brown: outer follicle surface (k) 

red: seed (l) 

tan: ovary wall (n)

Laurel Family (Lauraceae) 

Aromatic bark and leaves, and small flowers, with parts 

in whorls of three are characteristics of this family. A 

distinguishing feature of the family is the valvate anther 

dehiscence (see below in Sassafras). Plants are 

mostly evergreen, except in the Temperate Zone where 

they are deciduous. Forms are trees, shrubs, or vines. 

Usually, the leaves are alternate and have entire margins. 

There are about 32 genera with 2,500 species with 

most occurring in the tropics and subtropics of Southeast 

Asia and Brazil. 

The flowers are usually bisexual and develop as clusters 

in the leaf axils. A single flower has 6 sepal-petal 

parts and 12 stamens in 3 whorls. But one or two 

stamen whorls may be sterile “honey leaves” called 

staminodes. 

The single pistil usually has an ovary above the other 

flower parts (a superior position), containing one ovule 

in parietal placentation, one style and one stigma. For 

fruit types, there are drupes or berries, which are enclosed 

at the base by the persistent sepal tube. 

Of interest...aromatic oils: Cinnamomum camphorum 

(camphor), C. zeylanicum (cinnamon bark spice), 

Lindera Benzoin (spice bush), Laurus nobilus (bay 

laurel, bay tree, sweet bay), Persea spp. (avocado), 

Sassafras albidum (sassafras); ornamentals: 

Laurus, Lindera benzoin (spicebush), Umbellularia 

californica (California laurel); food: Persea americana 

(avocado); lumber: Beilschmiedia, Endiandra (walnut 

bean, oriental walnut), Litsea (pond spice), Ocotea 

rodioei (greenheart, was used to make the original 

gates of the Panama Canal locks), O. bullata (South 

African stinkwood). 

78 

Sassafras albidum Sassafras 

Before the deciduous leaves are shed, this tree is easily 

recognized by the shape of the alternate leaves (a). 

They are entire to five-lobed, and all types may be 

present on one plant. In autumn, the leaves turn yellow. 

The bark is thick, aromatic, and dark reddish brown. 

Bark of the roots was distilled for oil of sassafras, once 

used to flavor candy, root beer, and soap. Sassafras tea 

was popular, but now is regarded as possibly carcinogenic. 

Usually seen as a small tree along forest edges, 

it may reach a height of 30 meters. 

Unlike most members of the laurel family, sassafras has 

only male flower clusters or only female flower clusters 

on a plant. This is a dioecious condition (of two households). 

The male flower has 6 sepals (b) and 3 whorls 

of stamens; an outer whorl of 6 functional stamens (c), 

an inner whorl of 6 stalked, gland-like staminodes (d), 

and 3 more functional stamens (e) in the center. The 4 

cells (g) of the anther (h) have flap-like valves (i), that 

flip up to release pollen. 

Found on another tree, the female flower has 6 sepals 

(k), 6 staminodes (l), and a single pistil with an ovary 

(m) containing an ovule. At maturity, the ovule is the 

fruit of the purple drupe (q). This fruit is enclosed at the 

base by an expanded cup (r) made up of sepals and 

pedicel (s). 

COLOR CODE 

green: leaf (a), stem (u) 

yellow-green: sepals (b, k), stamens (c, e), pedicel 

(f, p), cells (g), anther (h), valves (i), 

filament (j) 

yellow: staminodes (d, l) 

pale green: ovary (m), style (n), stigma (o) 

purple: drupe (q) 

red: cup (r), pedicel (s), peduncle (t)

Water Lily Family (Nymphaeaceae) 

Water lilies are primitive, fresh water flowering plants. 

Long petioles are attached inside the blade margin 

(peltate leaf), or falsely so, permitting the leaves to float 

on the surface. The flower bud grows upward to the water 

surface on a long peduncle. Floating or submerged 

leaves are simple and alternate and often have milky latex 

ducts. These herbaceous plants are usually perennial. 

There are 9 genera and over 90 species. 

The flower is often showy, single and bisexual. Flower 

part numbers are indefinite, a primitive characteristic, 

but mostly in 3’s. The sepals are usually green and the 

ovary is usually superior. Fruits are follicles, an aggregate 

of indehiscent nutlets or a berry. 

Of interest...ornamentals: Brasenia (water shield), 

Cabomba (fanwort, used as an oxygenator in aquaria), 

Nelumbo lutea (lotus lily, water chinquapin), N. nucifera 

(oriental sacred lotus), Nuphar (yellow water lily, spatterdock), 

Nymphaea spp. (water lilies), Victoria amazonica 

(Amazon water lily, giant water lily); food: rhizomes 

of Nelumbo pentapetala were used a starchy 

food source by native Americans. 

Victoria amazonica, a native of the Amazon River in 

South America, was named after Queen Victoria of 

England when it was first discovered in 1801. Leaves 

may reach 7 feet (214 cm) in diameter. Leaf margins 

have upturned edges with notches that allow water to 

drain off the leaves. They live along river margins in 

shallow lakes. 

White flower buds open at sunset, heating to aid in 

spreading their strong sweet scent. This attracts the 

79 

main pollinator, a one-inch scarab beetle, Cyclocephala 

hardyi. As the flower temperature falls, the scent disappears; 

the flower closes with beetles trapped inside. 

The next day, the now dark pink flower reopens and 

releases the pollen-covered beetles, ready to fly off to 

another new white flower. 

Nymphaea odorata Water Lily 

This freshwater perennial plant has a stout underground 

stem (rhizome) with roots that anchor the plant in soil. 

Long petioles (a) make it possible for the buoyant leaf 

blades (b) to float on the water surface. The petiole is attached 

at a cleft in the blade where veins radiate from it. 

Large air passages run the length of both leaf petioles 

and flower peduncles (c) making them buoyant. Specialized 

parenchyma tissue with intercellular air spaces 

also aids water plants to float. 

The flower has 4 sepals (d), many petals (e), and many 

stamens (f). The outer whorls of stamens have smaller 

anther sacs and tend to be more petal-like than stamens 

of the inner whorls. The stamen’s filament (g) extends 

above the anther sacs (h). The inner, female part of the 

flower has a compound ovary (i) with many outwardly 

radiating carpels. A stigmatic surface (j, k) covers the 

upper portion of each carpel (l), which has numerous 

ovules (m) inside. 

After fertilization, the flower grows downward below the 

water surface to the mud substratum, where a manyseeded 

berry (n) matures. Sepals and petals disintegrate, 

leaving scars (o) on the outer surface. 

COLOR CODE 

tan: petiole (a), peduncle (c) 

green: blade (b) 

yellow-green: sepals (d), berry (n) 

light lavender: petals (e) 

dark lavender: petal tips (shaded), stamen tips 

(shaded) 

yellow: stamens (f), filament (g), anther 

sacs (h), ovary (i), stigmas (j), 

stigmatic surface (k), carpel (l) 

white: ovules (m)

Buttercup Family (Ranunculaceae) 

Plants in this primitive family are mostly annual or 

perennial herbs, but a few are woody vines. They prefer 

moist habitats. The leaves are usually alternate, compound, 

and have palmate venation. Typically, the flower 

is bisexual with spirally arranged parts. There are over 

50 genera and over 1800 species found in temperate 

and cold areas of the Northern Hemisphere. 

There are usually 5 sepals (but there may also be 

3 to many) and 5 petals or varying numbers or none. 

The petals sometimes serve as nectaries. There are 

many spirally arranged stamens. 

Pistils are 3 to many. The ovary is superior with one 

to many carpels and one to many ovules in parietal 

placentation. The fruits are follicles, achenes, berries, 

or capsules. 

Of interest...ornamentals: Aconitum (monkshood, 

extremely poisonous), Actaea (baneberry), Anemone 

(windflower), Anemonella (rue anemone), Aquilegia 

(columbine), Caltha (marsh marigold, cowslip), Clematis 

(clematis), Cimicifuga (bugbane), Coptis (golden 

thread), Delphinium (delphinium, larkspur), Helleborus 

(Christmas rose), Hepatica (hepatica), Hydrastis 

(golden seal), Isopyrum (false rue anemone), Nigella 

(love-in-a- mist), Paeonia (peony), Ranunculus (buttercup), 

Thalictrum (meadow rue), Trollius (globe flower). 

Ranunculus pensylvanicus Buttercup 

This wild plant is an erect, branched perennial growing 

30 to 70 centimeters high. Its hairy stem (a) has 

alternate leaves (b, c), which are deeply lobed forming 

three leaflets (d) that have toothed margins and palmate 

venation. 

The flower (f) has reflexed sepals (g) that are longer 

than the petals (h). Numerous stamens (i) surround the 

base of a central aggregate of numerous pistils (j). The 

carpel of each pistil has one ovule (k). At maturity, the 

fruit consists of an aggregate of achenes (m). 

80 

COLOR CODE 

light green: stem (a), pistils (j), ovules (k) 

green: petioles (b), leaflets (d), sepals (g), 

peduncle (l) 

tan: roots (e), achenes (m) 

yellow: flower (f), petals (h), stamens (i)

Witch Hazel Family 

(Hamamelidaceae) 

Trees and shrubs are represented in this family. There 

are 23 genera and about 100 species, mostly found 

in Asia. The alternate leaves are simple, deciduous or 

evergreen, and have deciduous, reduced leaves (stipules) 

at the petiole base. Often, star-like (stellate) or 

tree-like (dendrite) hairs occur on leaf surfaces. 

Flowers are bisexual or unisexual on the same plant 

(monoecious) or on separate plants (dioecious). 

Flower parts include 4-5 sepals, 4-5 petals or none, 

2-8 stamens, and a single pistil. 

Significant flower characteristics are a pistil with 2 styles 

that curve away from each other and an ovary consisting 

of 2 carpels and chambers that develop into a woody 

capsule. 

Of interest...extract: Hamamelis virginiana (witch 

hazel); lumber: Altingia excelsa (rasamala), Bucklandia, 

Liquidambar styraciflua (sweet gum); ornamentals: 

Corylopsis (winter hazel), Disanthus, Distylium, 

Fothergilla (fothergilla, witch alder), Hamamelis viriginiana 

(common witch hazel), H. vernalis (vernal witch 

hazel), Liquidambar styraciflua (sweet gum, with multicolored 

autumn foliage), Loropetalum, Parrotia, Sinowilsonia. 

Hamamelis virginiana Common Witch Hazel 

Forked branches of this shrub or small tree were used 

in the past as divining rods for water-well sites. An 

81 

astringent compound is extracted from leaves, stems, 

and bark for use in ointments and lotions. Leaves 

(a) have an uneven blade base (b) and microscopic 

dentrite hairs on the surfaces. 

In this autumn-flowering species, two-loculed capsules 

(d) mature from the previous year’s flowers at the same 

time as flower buds (e) are opening. As the capsule 

opens, two shiny seeds (f) are forcibly ejected. 

Hamamelis vernalis Vernal Witch Hazel 

Unlike the common witch hazel, this shrub’s flowers 

open in the spring. Stemless (sessile), bisexual flowers 

form in small clusters. Below each flower are hairy 

bracts (g). The flower parts include 4 triangular sepals 

(h), 4 strap-shaped petals (i), 4 stamens (j), which open 

(dehisce) by upward-turning anther valves (k), and a 

single pistil (m). 

The pistil has 2 styles (n) and stigmas (o) and a halfinferior 

ovary consisting of 2 carpels (p). In each carpel 

is an ovule (q) with axile placentation (see 28). After 

fertilization, the ovule will form the seed that is later 

ejected. Surrounding the ovary are 4 nectar flaps (r), 

which attract insect pollinators. 

COLOR CODE 

green: leaves (a), pistil (m) 

tan: stem (c), capsule (d), flower buds (e), 

bracts (g), peduncle (s) 

dark brown: seeds (f) 

dark red: sepals (h) 

yellow: petals (i), stamens (j), anther valves (k), 

filament (l), nectary (r) 

light green: style (n), stigma (o), carpel (p), ovule (q)

Elm Family (Ulmaceae) 

There are only about 16 genera in this family of trees 

and shrubs. Most of the genera have unisexual flowers. 

The alternate leaves usually have toothed (dentate) 

margins, uneven blade bases, and deciduous stipules. 

Parts of the flower include fused sepals of 4-8 lobes, 

stamens the same number as sepal lobes, and one pistil. 

The flower has no nectaries and no petals, but does 

have abundant pollen, that is wind-carried to the pistil’s 

plumose stigmas. A single ovule develops in a superior 

ovary consisting of two fused carpels. Fruit types are a 

winged samara, drupe, or nutlet. 

Of interest...lumber: Ulmus spp. (elms), Planera 

abelica (false sandalwood); ornamentals: Ulmus 

glabra (Scotch elm), U. parvifolia (Chinese elm); weed 

tree: Ulmus pumila (Siberian elm). 

Ulmus americana American Elm 

This once common American tree has been greatly reduced 

in numbers by the Dutch elm disease caused by 

an ascomycete fungus, Ceratocystis ulmi (see 48). 

The leaf has a short petiole (a), an uneven blade base 

(b) and doubly serrated margins (c). Its upper surface 

feels rough to the touch, while the lower surface is 

smooth. At the end of each growing season, the terminal 

bud falls off. The first lateral bud then forms a 

false “terminal” bud (d). This accounts for the zigzag 

stem (f) in elms. 

In the spring, clusters of tiny flowers (g) dangle out from 

the bud scales (h) before the leaves expand. Flowers 

are grouped in clusters (fascicles, i)of3or4.Thebisexual 

flower has 8 lobes (j) on joined sepals (k) and 

8 stamens (m) with the anthers (o) extended on long 

filaments (p). 

The pistil produces one ovule in the ovary (q) and has 

many stigmatic hairs along 2 styles (r). The fruit is a 

winged (s) samara with a single seed (t). It is winddispersed 

in the spring. 

Celtis tenuifolia Dwarf Hackberry 

This small tree has variably margined (entire and 

toothed) leaves (v) with lobed veins (w) and a drupe 

(x) type fruit which matures in the autumn. 

82 

COLOR CODE 

dark green: petiole (a), blade (b) 

tan: bud (d), lateral bud (e), stem (f), 

sepals (u) 

orange: sepal lobes (j) 

red: flowers (g), joined sepals (k) 

yellow-green: sepal base (l) 

brown: bud scales (h), seed (t) 

yellow: stamens (m), pollen (n), anther (o) 

white: filament (p), style (r) 

light green: ovary (q) 

yellow-tan: samara (s) 

green: leaf (v) 

orange-red: drupe (x)

Beech Family (Fagaceae) 

A nut fruit partially enclosed in basal bracts (acorn, 

beechnut, chestnut) is the most familiar characteristic 

of this family of eight genera. Genera are Fagus 

(beech), Castanea (chestnut), Quercus (oak), Lithocarpus, 

Nothofagus, Castanopsis, Trigonobalanus, and 

Chrysolepsis. Fossils indicate an origin during the middle 

of the Cretaceous. 

Alternate, simple leaves have lobed, toothed, or entire 

margins and deciduous stipules. The flowers are usually 

unisexual and wind-pollinated. 

The male flower occurs in catkins or singly and has 4–7 

sepals, 4–40 stamens, and a vestigial pistil. The female 

flower can be single in a cup of bracts or in a cluster of 

2–3 flowers, which may have bracts. Fused sepals of the 

female flower have 4–6 lobes. The pistil has an inferior 

ovary of 3–6 carpels, chambers (locules), and styles. 

Two ovules occur in axil placentation. They develop in 

each chamber, in which one develops and the other 

aborts. 

Of interest...hardwood lumber: Castanea spp. 

(chestnuts), Fagus spp. (beeches), Quercus spp. (oaks; 

in the United States, oaks are the second most important 

source of lumber after conifers); food: nuts 

of chestnut, beech and oaks. Native Americans used 

acorns to make bread. Acorns are also an important 

source of food for wild animals and birds. Commercially, 

Castanea sativa (sweet chestnut), of southern 

Europe, is a source of nuts for purees, stuffings 

and stews; cork: bark of Quercus suber (cork oak) is 

stripped and dried to produce cork; ornamentals: Castanea 

spp. (chestnuts), Fagus spp. (beeches), Lithocarpus 

(tanoak), Quercus spp. (oaks); plant diseases: 

Castanea dentata (American chestnut) has been 

83 

devastated to near extinction by chestnut blight, caused 

by an ascomycete fungus, Endothia parasitica (see 48); 

sudden oak death is a disease caused by Phytophthora 

ramorum, an oomycete (see 46). 

Quercus spp. Oaks 

Oak forms vary from small shrubs to large trees. They 

have deep roots and occur in dry sites. There are over 

400 species and many hybrids between species. Oaks 

are easily identified, even in winter, by the cluster of 

buds (a) at the end of the stem (c). The leaves (e, f, g) 

are deciduous or persistent. Young oaks tend to retain 

their leaves over winter and shed them in spring. 

Oaks are divided into two groups: white oaks and red 

oaks. White oaks have leaves with rounded lobes and 

acorns that mature in the autumn of their first year. Red 

oak leaves have bristle tips and acorns that mature in 

the autumn of the second year. 

Oaks are monoecious with separate male and female 

flowers on one tree. Male flowers form in pendant clusters, 

an indication of wind pollination. The male flowers 

(h) open before or with expanding leaves (k). The male 

flower has four to seven sepals (m) and six to twelve 

stamens (n). 

The female flowers form in the axils of new spring 

leaves. This flower has joined sepals of 6 lobes (o) and 

a pistil consisting of 3 styles (p) and 3 stigmas (q). The 

ovary is enclosed in a whorl of bracts (involucre, r) 

which matures into a scaly cup (s). The fruit of cup and 

nut (t), commonly known as an acorn, may mature in 

one or two seasons. 

COLOR CODE 

tan: buds (a, b), leaf scar (d), leaf (g), 

cup (s) 

brown: stem (c), peduncle (l) 

green: leaf (e) 

red: leaf (f) 

yellow: male flowers (h) 

light tan: stem (i), sepals (m), nut (t) 

tan-orange: bud scales (j) 

grey-green: young leaves (k) 

yellow-green: stamens (n) 

light green: sepals (o), styles (p), stigmas (q), 

involucre (r)

Birch Family (Betulaceae) 

Trees and shrubs that comprise this family have 

deciduous leaves. Leaves are alternate and simple and 

have saw-tooth (serrate) margins. Stipules are present 

at petiole bases. The bark is prominently marked by 

lenticels (openings for gas exchange) and in some 

species it peels off in thin papery layers. There are 

six genera with about 170 species. Genera are Alnus 

(alder), Betula (birch), Carpinus (hornbeam), Corylus 

(hazelnut, filbert), Ostrya (hop-hornbeam), and 

Ostryopsis. 

The flowers in this family are borne in catkin-like clusters 

of cymules. Many cymules make up a cyme (cluster of 

clusters). Each cymule has two to three flowers and 

several bracts. Clusters of male flowers and clusters of 

female flowers occur on the same plant (monoecious). 

The male flower may have 4 tepals (sepals and petals 

that look alike) with 2–20 stamens per cyme. The female 

flower has a single pistil with an inferior ovary, 2 

styles, and 2 stigmas. These spring flowers utilize wind 

for pollination and produce a nutlet or a winged samara 

fruit. 

Of interest...lumber: Betula (birch), Alnus oregona 

(red alder), Ostrya (hop-hornbeam); charcoal: Alnus 

(alder), Betula; food: Corylus (hazelnut, filbert); ornamentals: 

Betula papyrifera (paper birch, white birch), B. 

pendula (European white birch), B. nigra (river birch), 

Corylus, Ostrya. 

Betula pendula European white Birch 

This tree, often used as an ornamental, has several 

trunks typically occurring together in a clump. The white 

paper bark has dark horizontal lenticular markings and 

peels off in layers. Trees have graceful spreading or 

pendant branches. 

The flowering shoot (a) shows the leaves (b) with serrated 

(toothed) margins and stipules (c). Male flower 

clusters (catkins, d) are pendant, while the female cluster 

(e) is smaller and upright. The male cyme shown has 

7 stamens enclosed by bracts (f). At the end of the stamen’s 

filament (g), 2 anther sacs (h) separate and open 

in longitudinal slits. Three pistils and 3 bracts (i) make 

up the female cymule. The pistil has an inferior ovary 

(j) and 2 styles (k). 

At fruiting time, the female cluster disintegrates, freeing 

the samaras (l) from the woody bracts (m). 

84 

COLOR CODE 

tan: stem (a), male cluster (d), bract (f), 

seed (n) 

green: leaves (b), stipules (c), female cluster (e) 

yellow: filaments (g), anther sacs (h), samara (l) 

dark green: bract (i) 

white: ovary (j), styles (k) 

brown: bracts (m)

Cactus Family (Cactaceae) 

Native only to the Western Hemisphere, cacti have 

fleshy stems with spines or barbed hairs (glochids) arranged 

in cluster sites (areoles). Spines may occur as 

hairs, hooks, bristles, and be short, straight, curved, 

long. They shade the plant and reduce drying effects of 

wind. The usually solitary flower has numerous sepals 

and petals that look alike (tepals) and the fruit type is 

a berry. 

As the stems usually function in photosynthesis, the 

leaves are mostly small, scale-like, or absent. Root systems 

are usually extensive and close to the soil surface, 

adapted to absorb rainwater quickly. 

To prevent water loss in dry climate conditions, there is 

an outer surface cuticle that is thick and waxy. Water 

absorbed by the roots is stored in tissue as mucilaginous 

sap. 

Of interest...cacti number about 80 genera with 

at least 2,000 species; a few of the ornamentals 

are: Echinocereus, Echinopsis, Ferocactus sp. (barrel 

cactus), Lemaireocereus thurberi (organpipe cactus), 

Mammillaria (pincushion cactus), Neoporteria, Opuntia 

versicolor (staghorn cactus), Peniocereus greggii 

(night blooming cereus), Pereskia (rose cactus), 

Rubutia (red crown cactus), Schlumbergera bridgesii 

(Christmas cactus); food: Opuntia (prickly-pear) has 

edible berries, that can be made into jam; young stems, 

“pads,” are eaten as food, and can be propagated by 

drying overnight, then placed in sand to root; considered 

a weed pest on rangeland; many are endangered: 

Carnegiea gigantea (saguaro, see 36). 

There are many forms of cacti: single, clumps, low to the 

ground, upright, even tall as trees such as Carnegiea 

gigantea (saguaro). At an age of 200 years saguaro 

can reach 50 feet (152 meters) high and weigh 8 tons 

85 

(45 tonnes). “Skeletons” of dead saguaro stem look like 

cylinders of woody rods. People of the desert use them 

as fence-building material. 

Birds nest in cacti. Even though cactus spines deter 

contact, squirrels and other rodents, rabbits, and peccaries 

eat the fleshy stems. 

The cactus craze began in the 1800’s. Hobbyists collect 

different types of cacti. Cacti are easy to grow, needing 

sparse water, sandy soil, and produce beautiful flowers 

in many colors. And, they are perennials. 

Cacti are transported to other desert areas of the world. 

In some places they are serious invaders, displacing 

native species. 

Opuntia decumbens Prickly-pear 

The fleshy stem (a) is flat. A stem node in cacti is called 

an areole (b). From it emerges a leaf (c), if present, 

spines (d) and glochids (reduced short shoots), hairs 

(e), and the flower. 

Schlumbergera truncata Thanksgiving Cactus 

On this plant, the stems (f) are flat and form a branching 

pattern as new stems emerge from areoles at ends 

of the stem pieces. With short daylength periods, flowers 

are produced (see 26). The flower has numerous 

tepals (g), numerous stamens (h), and a single pistil. 

The stigma (i) of the pistil extends beyond the stamens. 

Pereskia grandifolia Rose Cactus 

This cactus plant has round fleshy stems (j) with spines 

(k) and a large thickened simple leaf (l) emerging from 

the areole. 

COLOR CODE 

light green: leaf (c) 

green: stem (a, f, m j), leaf (l) 

yellow: areoles (b), spines (d, k), hairs (e) 

red: tepals (g)

Cactus Family (continued) 

Mammillaria prolifera Pincushion Cactus 

This perennial herb from North American deserts is 

globe-shaped. Areoles (a), with hairs (b) and glochids 

(c), occur raised on fleshy tubercles (d). 

The typically bisexual cactus flower consists of numerous 

tepals (e), numerous stamens (f), and one pistil 

with an inferior ovary (g) consisting of three fused 

carpels forming one chamber (locule) in which numerous 

ovules (h) develop in parietal placentation. The pistil 

has one style (i) and a branched stigma (j). 

The fruit is a red berry (k) with black seeds (l). 

Of interest...houseplants: there are many species to 

choose from with flower colors from white to cream, 

reds, pinks and yellows. They are easy to grow in 

porous, sandy/gravely soil. Some include Mammillaria 

albescens (greenish-white flowers), M. bocasana ‘Inermis’ 

(snowball cactus, yellow flowers), M. columbiana 

(deep pink flowers), M. compressa (purplish-red flowers), 

M. elegans (red flowers),M. geminispina (carmine 

flowers), M. heyderi (coral cactus, white with red or 

pink flowers), M. magnimamma (cream-white flowers), 

M. zeilmanniana (rose-pincushion, purple flowers). 

86 

COLOR CODE 

tan: glochids (c) 

pale green: tubercles (d) 

yellow: tepals (e) 

white: stamens (f), ovules (h), style (i), 

stigma (j) 

red: berry (k)

Pink Family (Caryophyllaceae) 

Leaves of plants in this family are usually opposite and 

joined at the base on the stem. The flower’s ovary has 

2–5 carpels joined to form one chamber (locule) with 

the ovules usually in free-central placentation (see 28 

and Dianthus). There are more than 2,000 species. 

This is one of the families in the subclass Carophyllidae 

that does not have betalain pigments (see 75). 

Instead, there are anthocyanins (see 4). These Temperate 

Zone plants are mainly annual or perennial 

herbs, or sometimes shrubs. The fruit is usually a onechambered 

capsule with valves. 

Of interest...ornamentals: Arenaria (sandwort), 

Dianthus barbatus (sweet William), D. caryophyllus 

(carnation), D. gratianopolitanus (cheddar pink), D. 

plumarius (cottage pink), Gypsophila (baby’s-breath), 

Lychnis chalcedonica (Maltese Cross), L. coronaria 

(rose campion, dusty miller), Silene acaulis (cushion 

pink); weeds: Cerastrium (mouse-ear chickweed), 

Scleranthus, Stellaria (chickweed, starwort), Spergula 

arvensis (corn spurry), Silene pratensis (white 

cockle); prairie plants: Dianthus armeria (Deptford 

pink), Silene dioica (red campion), S. latifolia 

(evening campion), S. regia (royal catchfly), S. stellata 

(starry catchfly), S. virginica (fire pink); poisonous: 

87 

Agrostemma githago (corn cockle), Crymaria pachyphylla, 

Saponaria vaccaria (cow cockle), S. officinalis 

(bouncing Bet). 

Dianthus Pink 

Plants in this genus are annual or biennial herbs. The 

arrangement of leaves (a) on the stem (b) is decussate, 

which means 4 pairs of opposite leaves alternate at right 

angles. Leaf bases form swollen nodes (c) on the stem. 

The bisexual flower has 5 joined sepals (d) and overlapping 

bracts (e) that prevent nectar-robbing bees from 

biting into the flower. The illustration of the capsule 

shows the sturdy construction. The 5 petals (f) are 

notched or “pinked” at the edges as if cut by pinking 

shears and consist of claw (g), corona (h) and limb (i). 

Ten stamens (j) have 5 joined filaments at the base. 

The pistil has a superior ovary (k) with carpels united 

into one locule in which many ovules (l) are attached in 

free-central placentation. Two styles (m) elongate into 

feathery (plumose) stigmas (n). 

The capsule is enclosed by sepals and bracts and splits 

into valves (o) adapted to release the seeds. 

COLOR CODE 

dark green: stem (b) 

green: leaves (a), nodes (c), sepals (d), bracts 

(e) 

red: petals (f), claw (g), corona (h), limb (i) 

yellow: stamens (j) 

light green: ovary (k) 

white: ovules (l), style (m), stigmas (n) 

tan: valves (o)

Goosefoot Family (Chenopodiaceae) 

Plants in this family are mainly salt-tolerant annual or 

perennial herbs with vesicular (glandular) hairs on the 

leaves that store salt as sodium or potassium chloride. 

Betalain pigments are also present (see 4, 75). This 

family has about 100 genera and about 1500 species. 

Tiny, wind-pollinated flowers form in dense clusters. The 

usually bisexual flower has 5 joined sepals or none, 5 

stamens, and a single pistil. In the superior ovary is one 

chamber (locule) containing one ovule that develops 

into a nutlet fruit. 

Of interest...food: Beta vulgaris (beet, eaten as a 

vegetable and also as a sugar beet variety that is a 

source of sugar), Beta vulgaris variety Cicla (Swiss 

chard, rhubarb chard), Chenopodium quinoa (quinoa), 

Spinacia oleracea (spinach), Tetragonia expansa (New 

Zealand spinach); wild food: Chenopodium album 

(lamb’s quarters); ornamental: Chenopodium amaranticolor, 

Kochia (cypress spurge). 

Chenopodium album Lamb’s Quarters 

This annual herb grows to one meter in height and is 

found in dry, waste places and as a common garden 

weed. The 5-sided stem (a) has alternate, “goose-foot”shaped 

leaves (b) with white spots of salt-containing 

glands (c) on the lower surfaces (d). 

Spikes of sessile green flowers (e) produce black, shiny 

nutlets. The flower consists of 5, gland-covered sepals 

(f), 5 stamens (g) and a single pistil with a superior ovary 

(h), and 2 styles (i). 

Chenopodium capitatum Strawberry-blite 

Also an annual, this plant is found along roadsides and 

in clear-cut and burned-over forest areas. Its alternate 

“goose-foot” leaves (k) lack salt-containing glands. 

Round clusters of flowers (l) are bright red, the color 

of the flower’s fleshy sepals. Dull black nutlets (m) are 

produced. 

88 

COLOR CODE 

green: stems (a, j), leaf upper surface (b), 

leaves (k) 

pale green: leaf lower surface (d), flowers (e), 

sepals (f), ovary (h), styles (i) 

yellow: stamens (g) 

red: flowers (l) 

black: nutlet (m)

Buckwheat Family (Polygonaceae) 

Most of the family’s plants are weedy with small flowers 

and are adapted to many different soil types. The stem 

nodes have a sheathing membrane consisting of two 

fused stipules, called an ocrea. While mainly herbs, 

there are also a few shrubs, trees, and vines in this 

family. There are about 30 genera. 

Small, wind-pollinated flowers are borne in clusters or 

in heads. Usually the flower is bisexual and with a variable 

number of parts of 3-5 sepals and petals that look 

alike (called tepals), 6-9 stamens, and a single pistil. 

The superior ovary of fused carpels has one chamber 

(locule) with one ovule which develops into an achene 

fruit (see dry fruit types, 38) 

Of interest...food: Fagopyrum esculentum (buckwheat), 

Rheum rhaponticum (rhubarb), Rumex acetosa 

(garden sorrel); ornamentals: Antigonon (mountainrose 

vine), Atraphaxis frutescens, Coccoloba uvifera 

(sea grape), Eriogonum, Muehlenbeckia axillaris, Persicaria 

bistorta ‘Superba’ (knotweed), Polygonum aubertii 

(silver lace vine), P. orientale (prince’s feather), P. 

sachalinense (sacaline), Rheum palmatum (Chinese 

rhubarb, a medicinal plant), Rumex hydrolapathum; 

weeds: Polygonum spp. (knotweeds, smartweeds, wild 

buckwheat), Polygonum convolvulus (black bindweed), 

Rumex acetosella (sheep sorrel, red sorrel, an edible 

plant with tart-tasting, arrowhead-shaped leaves), R. 

crispus (curly dock). 

Polygonum persicaria Lady’s Thumb, Redleg 

Lady’s thumb is known as a smartweed for its sap, which 

irritates, “smarts,” on contact with human eye and nose 

tissues. This annual’s stems (a) have a jointed appearance. 

Polygonum means “many joints” or “knees,” the 

name given for the knobby stems with swollen nodes. 

At each node (b) is an ocrea (c) fringed with bristles. 

Short-petioled, linear leaves (d) have a spot (e) of dark 

green pigmentation near the center, the so-called lady’s 

thumb-print. 

Pink flower clusters (f) have a minute membranous 

sheath (ocreola, g) at the base of inner clusters. The 

small flower has 5 tepals (h), 2 enclosing the inner 3; 

8 stamens (i); and a single pistil (j) with 2 stigmas (k). 

The fruit is an achene that may be lentil-shaped (l) or 

3-sided (m). 

89 

COLOR CODE 

green: stem (a), leaf (d) 

light green: ocrea (c), ocreola (f), pistil (j) 

dark green: spot (e) 

pink: flowers (f), tepals (h) 

white: stamens (i) 

black: achene (l) 

tan: achene (m)

Mallow Family (Malvaceae) 

The flower’s column of fused staminal filaments is a 

common feature in this family (see 29). The leaves are 

alternate, simple, entire or variously lobed with palmate 

venation. Sap is often mucilaginous. There are about 

80 genera of herbs, shrubs and trees. 

Usually the flower is bisexual with 5 valvate sepals, 5 

separate petals, numerous stamens, and a single pistil 

with 2-many carpels. Fruit types include a loculicidal 

capsule, often with hairy (comose) seeds as in cotton, 

a schizocarp, and a berry (see 38, 39). 

Of interest...crops: Gossypium hirsutum (cotton, cottonseed 

oil), Hibiscus esculentus (okra); ornamentals: 

Abutilon (flowering maple), Althea rosea (hollyhock), 

Callirhoe (poppy mallow), Hibiscus moscheutos (common 

rose mallow, swamp mallow, mallow rose), M. 

rosa-sinensis (rose-of-China, see 29), Malope, Malva 

alcea (hollyhock mallow), M. moschata (musk mallow), 

Sidalcea malviflora (prairie mallow, miniature hollyhock); 

weeds: Abutilon theophrasti (velvet-leaf), Malva 

neglecta (common mallow, cheese weed). 

Abutilon × hybridum Flowering Maple 

This plant is a tropical woody shrub, hybridized in cultivation 

for its speckled (a) leaves and showy flowers. 

Resembling maple leaves (maple family, see 105), the 

90 

blades (b) are palmately lobed and veined; the petioles 

(c) are long. 

Showy orange flowers have 5 joined sepals (d), which 

separate into valves and 5 petals (e). Anthers (f) extend 

from the center of the flower. 

In the vertical section of the flower, the column (g) 

of fused staminal filaments (monadelphous condition) 

is shown. Anthers (h) are separate at the top of the 

column. Within the column is the pistil’s style (i) and, 

emerging above the anthers, there are 5 stigmas (j). 

The superior ovary (k) is composed of 5 fused carpels, 

and has numerous ovules (l). 

Althea rosea Hollyhock 

The numerous carpels of a compound ovary produce 

a schizocarp fruit (see 38) of seeded mericarps (m) 

attached to a central axis and enclosed by persistent 

sepals (n). When the sepals wither, the mericarps separate 

from the axis. 

Gossypium hirsutum Cotton 

A cotton “boll” is a loculicidal capsule (o) of 4 carpels 

that split to release hair-covered (p) seeds (q). 

COLOR CODE 

yellow: speckles (a) 

green: leaf blades (b), petioles (c) 

pale green: sepals (d, n), ovary (k), style (i) 

dark red: stigmas (j) 

orange: petals (e) 

pale orange: column (g), anthers (f, h) 

white: hairs (p), ovules (l) 

tan: mericarps (m), seed (q) 

brown: capsule (o)

Pitcher-plant Family (Sarraceniaceae) 

Although there are only three genera in this family, these 

perennial herbs of bogs are of interest for their unusual 

insect-trap leaves. Forming in a basal rosette, the 

fluid in the modified leaves digest insects for nutritional 

nitrogen. 

The bisexual flower consists of 4-5 sepals, 5 petals or 

none, numerous stamens, and a single pistil. The style 

is lobed or expands into an umbrella-shape. A loculicidal 

capsule is formed from 3-5 carpels. 

Of interest...as novelty ornamentals, pitcher-plant 

genera are: Darlingtonia (native to California and 

Oregon), Heliamphora (native to northern South 

American), and Sarracenia (native to eastern North 

America). 

Sarracenia purpurea Pitcher-plant 

Early in leaf development, the blade forms a tube with 

the upper leaf surface on the outside and the hairy 

lower surface on the inside. Within the leaf tube (a), with 

downward-pointed hairs (b), is a solution (c) of rainwater 

and enzymes in which insects drown and are digested. 

The leaf consists of petiole (d) and blade tube (e), wing 

(f), and lip (g). It is pale green with red veins (h). 

Appearing as a hanging umbrella covered with flaps, 

the flower towers above the leaves on a long peduncle 

(i). The flaps are 5 sepals (j). In the habit drawing, the 5 

petals (k) and numerous stamens (l) have been shed. 

The flower structure drawing shows their location. The 

pistil consists of a superior ovary (m) composed of 5 

carpels (n) with ovules (o) in axile placentation, and an 

expanded, umbrella-shape style (p, q) with 5 stigmatic 

tips (r). 

91 

COLOR CODE 

red: hairs (b), veins (h), sepals (j), petal (k) 

light green: petiole (d), tube (e), wing (f), lip (g), 

peduncle (i), style (p, q), stigma (r), 

blue: liquid (c) 

white: ovules (o) 

yellow: stamens (l)

Violet Family (Violaceae) 

Members of this family are herbs and shrubs and usually 

perennial. Leaf-like appendages (stipules) occur 

at the base of simple, usually alternate leaves. 

Violet flowers are bisexual with flower parts in 5’s. The 

lowermost petal is often spurred. The flower’s pistil has 

a superior ovary of 3–5 fused carpels. The stamens, 

close around the pistil, are connected at the base and 

open inwardly. The fruit is a one-chambered capsule or 

a berry. 

Of interest...ornamental: Viola spp. (pansies, violets); 

essential oils: Viola oderata, grown for oil in the 

manufacture of perfumes, flavorings, and liqueur; food: 

Viola (leaves and flowers are edible, containing copious 

amounts of vitamins A and C) and crystallized flowers 

are used for decoration; wild: Hybanthus (green violet), 

Rinorea, Viola spp. (violets). 

Viola papilionacea Common Blue Violet 

This perennial herb has a horizontal rhizome (a) and 

produces flowers in the spring and fertile cleistogamous 

flowers in the summer and fall. Cleistogamous 

flowers are small, lack petals, do not open, are selfpollinated 

and occur near the base of the plant in soil 

substratum. 

92 

The leaf blades (b) have heart-shaped bases with scalloped 

margins and are attached to long petioles (c) with 

stipules (d) at the bases. 

Flowers are borne on long peduncles (e) that arise from 

the base of the plant. The 5 sepals (f) have small projecting 

lobes (auricles, g). There are 5 unequal petals 

(h) with the 2 lateral petals bearded with hairs (i) the 

base. The lower petal has a spur (j). (See bud drawing.) 

Purple nectar guides converge toward the base of 

the white-throated petals. 

Five basally-fused stamens (k) enclose the ovary (l) 

(shown in a cross-section) and the style (m). The end 

of the style is enlarged and on the lower side is a beak, 

the stigma (n). Two of the stamens have nectar horns 

(o), which project into the lower petal spur (j). Pollen 

from the stamens sheds into the inner cone. 

As an insect probes for nectar, it moves the stigma 

aside and pollen in the cone sticks on its tongue. Crosspollination 

results when the next flower is visited. 

The pistil’s ovary (l) has 3 fused carpels with many 

ovules (p) in parietal placentation. At maturity, the fruit 

is a loculicidal capsule (q) with numerous seeds (r). 

COLOR CODE 

white: rhizome (a), roots, stipules (d), beards 

(i) ovules (p) 

light green: petioles (c), peduncles (e), stamens (k), 

nectar horns (o), style (m), stigma (n) 

green: leaves (b), sepals (f, g) 

violet: petals (h), capsule (q) 

violet-brown: petal spur (j), ovary (l) 

dark brown: seeds (r)

Begonia Family (Begoniaceae) 

This family of plants is native to the tropics and subtropics 

across the continents. It is popularly known for its 

Begonia cultivars grown as house plants. Plants in this 

family are perennial herbs or small shrubs. Most have 

succulent stems with alternate leaves and with deciduous 

stipules. Leaves are mostly palmately veined and 

usually asymmetrical with an oblique base. 

Unisexual male and female flowers occur on the same 

plant (monoecious). The male flower has 4 irregular 

tepals and many stamens in whorls. The pistil of the 

female flower has an inferior, angled or winged ovary 

consisting of usually 3 carpels and twisted stigmas. Fruit 

types are a loculicidal capsule and a berry. 

Of interest...there are over 900 species within five 

genera: Begonia, Begoniella, Hillebrandia, Semibegoniella 

and Symbegonia; ornamental: Begonia (begonia) 

species are widely hybridized in horticulture 

for flowering and foliage plants. Flowering plants are 

tuberous- and fibrous-rooted, such as B. semperflorens 

(wax begonia) and B. tuberhybrida (tuberous begonia). 

Foliage plants have rhizomes, such as B. rex (rex begonia) 

cultivars. 

Begonia semperflorens cultivar ‘Scarletta’ 

This small plant flowers continuously (semperflorens 

= always flowering). Its waxy leaves (a, b) are 

93 

alternate and 2-ranked, which means the leaves arise 

in one plane on opposite sides of the succulent stem 

(c). At the petiole (d) base is a pair of stipules (e). Veins 

(f) of the leaf blade radiate out from a common point 

(palmate venation). Winged capsules are also shown 

on the stem portion. The stalk (peduncle, g) supporting 

a cluster of flowers or capsules has bracts (h) where the 

flower stems (pedicels, i)arise. 

A male flower has 2 petal-like sepals (j) and 2 smaller 

petals (k), together called tepals, and about 20-30 stamens 

(l). The stamen’s anther sacs (m) open (dehisce) 

longitudinally and have an enlarged connective (n) between 

them. There is a short filament. 

The four remaining drawings illustrate parts of the female 

flower. At the base of the flower are 3 bracts (p, 

x). Extending from the pistil’s inferior ovary are 3 unequal 

wings (q, v–w, z) partially covered by 5 tepals 

(r, y). The pistil’s 3 styles each have 2 twisted stigmas 

(s, t). 

A cross-section of an ovary shows the 3 carpels (u) with 

numerous ovules. As the flower matures, pigments fade 

in the ovary wings (v, w) and bracts (x), and the tepals 

(y) wither. The capsules (z) have a papery texture and 

contain many seeds. 

COLOR CODE 

dark green: upper blade surface (a) 

green: lower blade surface (b), stem (c) 

light green: petiole (d), peduncle (g), pedicel (i), 

inner ovary wing (v) 

tan: stipules (e), bracts (h, x), tepals (y), 

capsule (z) 

red: tepals (j, k, r), bracts (p), ovary wings (q) 

yellow: stamens (l), anther sacs (m), 

connective (n), filament (o), stigma (s, t) 

white: carpels (u) 

red-brown: outer ovary wing (w)

Gourd Family (Cucurbitaceae) 

Plants in this family are mostly perennial herbaceous 

vines with spirally coiled tendrils. Tendrils are modified 

stipules (see 23) that may be simple, forked or 

branched. Leaves are alternate, with usually palmate or 

pinnate venation. Plants lie flat (prostrate) and creep 

or climb (scandent). There are about 100 genera with 

over 700 species. 

Separate male and female (unisexual) flowers are most 

common in this family. This is a monoecious condition. 

Male flowers have unusual stamens. Where there may 

be 1-5, there are usually 3 stamens with one stamen 

having a one-chambered anther of 2 pollen sacs and 

2 stamens with 2-chambered anthers of 4 pollen sacs 

each. 

The female flower’s pistil has an inferior ovary consisting 

of 3-5 carpels, usually united into a single chamber 

(locule) of ovules in parietal placentation. 

The fruit is a berry with a soft fleshy pericarp or with 

a hardened pericarp and classified as a pepo. Before 

Linnaeus’ classification system, pepo was the name for 

pumpkin. Pepos that are dried for ornamental use or 

hollow vessels are commonly called gourds. 

Of interest...economically important as food:Citrullus 

lanatus (watermelon, citron), Cucumis anguiria (West 

Indian gerkin), C. melo (cantaloupe, honey-dew 

melon, melon), C. sativus (cucumber), Cucurbita spp. 

(pumpkins, squashes, vegetable marrows, vegetable 

spaghetti); ornamentals: gourds: Benincasa (Chinese 

94 

watermelon), Coccinea (ivy gourd), Lagenaria siceraria 

(calabash gourd, one of the earliest cultivated plants, 

dried to use as containers), Luffa cylindrica (loofah, 

dishcloth gourd, used as a dried sponge), Momordica 

(balsam apple), Sechium (chayote), Sicana (cassabanana), 

Sicyos (bur cucumber), Trichosanthes (snake 

gourd); T. kirilowii, the tree-of-joy from China, is an important 

anti-cancer plant containing the drug, trichosanthin. 

Cucumis sativus Cucumber 

The hairy stems (a) of this plant climb by means of tendrils 

(b) that arise at the petiole (c) bases. Five-lobed 

leaf blades (d) have palmate venation. Both male and 

female, unisexual flowers occur on the same plant (monoecious). 

A flower bud and a young female flower are 

on the shoot that is illustrated. 

Male flowers have 5 sepals, 5 petals (f), and 3 stamens 

(g). The stamens’ stout filaments (h) arise from 

the petals with the anthers joined together in the center 

of the flower. The stamen illustrated has a 2-chambered 

(bilocular) anther (i) with 4 pollen sacs (j). 

The female flower has 5 sepal lobes (k), 5 petals (l), 

and a single pistil. The pistil’s inferior ovary (m) consists 

of 3 united carpels (n) with ovules (o) in parietal 

placentation. Glandular hairs (p) dot the ovary surface. 

Inside the fused sepal base (k) is a nectar disc (q). The 

style (r) emerges above and terminates in a 3-lobed 

stigma (s). After fertilization, the ovary develops into a 

pepo, the familiar cucumber fruit (see 39). 

COLOR CODE 

green: stem (a), petiole (c), leaf blade (d), 

peduncle (e), sepals (k), ovary (m) 

light green: tendril (b), filament (h), anther (i, j), 

glandular hairs (p), style (r), stigma (s) 

yellow: petals (f, l), stamens (g), disc (q) 

white: carpels (n), ovules (o)

Willow Family (Salicaceae) 

Plants in this family are woody trees or shrubs that 

are dioecious, producing male and female flowers on 

separate plants. Specialized and reduced, unisexual 

flowers are aggregated into catkins (aments). Leaves 

are alternate, simple, and deciduous with stipules and 

petioles. 

Familiar plants include the aspens, poplars and willows. 

There are four genera. In the North Temperate Zone are 

Populus with 300 species and Salix. In Northeast Asia, 

Chosenia and Toisusu occur. 

Populus flowers are wind-pollinated, while Salix flowers, 

with nectar glands, are insect-pollinated. The fruit 

is a 2-4-valved capsule with numerous, hairy (comose) 

seeds. 

Of interest...ornamentals: Salix spp. (willows) with 

familiar species, S. babylonica (weeping willow), S. 

discolor (pussy-willow); Populus spp. (poplars, cottonwoods, 

aspens), P. grandidentata (large-toothed 

aspen), P. deltoides (cottonwood), P. tremuloides (quaking 

aspen); pulpwood: Populus tremuloides (quaking 

aspen), P. balsamifers (balsam poplar); wickerware 

and basket-making: Salix (willow); aspirin: acetylsalicylic 

acid was originally derived from the bark of Salix 

alba (white willow). 

Salix Willow 

The leaves (a) are alternate on the stem (b) and have 

toothed (dentate) margins. Flowers (c) of this male 

catkin have 3 stamens (d) with a hairy bract (e) and 

a nectar gland (f) below. 

The flowers (g) of the female catkin each have a single 

pistil with numerous ovules (h) in the ovary (i), a single 

style (j) and 2 stigmas (k). At the base of the flower 

pedicel (l) is a bract (m) and a nectar gland (n). With the 

evolutionary reduction of parts, these specialized flowers 

consist of only stamens or a pistil and are without 

sepals and petals. 

During spring, the female catkin becomes a fuzzy mass 

of hairy (comose) seeds (o) released from 2-valved (p) 

capsules to be dispersed by wind. 

95 

COLOR CODE 

green: leaf (a), female catkin flowers (g), 

pedicel (l) 

brown: stem (b), capsule valves (p) 

yellow: male flowers (c), stamens (d) 

dark brown: bracts (e, m) 

light green: nectaries (f, n), ovules (h), ovary (i), 

style (j), stigmas (k) 

tan: seed (o)

Mustard Family (Brassicaceae) 

The old family name, Cruciferae, refers to the cross form 

(cruciform) of the 4 diagonally opposed petals. Flowers 

also have 4 sepals. Stamen number and lengths and 

the single pistil’s ovary with a false partition are notable 

characteristics found in this family (the illustrated plant 

shows these features). The specialized type of fruit produced 

from the ovary is a narrow silique or a round 

silicle, in which seeds are separated into 2 chambers 

by a partition and covered on each side by a valve (see 

dry fruit types, silique, 38). 

This family consists of annual, biennial, or perennial 

herbs with pungent oils in the sap. There are about 380 

genera and about 3,000 species. The leaves are alternate 

and simple and usually have forked or star-like, 

one-celled hairs. 

Of interest...food: Armoracia rusticana (horseradish); 

Brassica nigra (mustard); Brassica napus 

(rape, rapeseed oil, canola oil); Brassica oleracea 

(wild cabbage, colewort) selected varieties produced 

such cole crops as B. capitate (head of 

leaves—cabbage), B. acephala (without a head— 

kale), B. botrytis (cluster of white flower buds— 

cauliflower), B. gemmifera (axillary buds—Brussels 

sprouts), B. italica (green flower buds—broccoli), 

B. caulorapa (swollen stem—kohlrabi), B. napobrassica 

(rutabaga); Eruca sativa (arugula); Nasturtium 

officinale (water cress); Raphanus sativus (radish); 

weeds: Alliaria petiolata (garlic mustard); Brassica 

spp. (wild mustards), Capsella bursapastoris (shepherd’s 

purse), Lepidium densiflorum (pepper-grass), 

Draba (hoary cress), Thlaspi arvensis (penny cress); 

ornamentals: Arabis caucasica (rock cress), Aubrieta 

(false rockcress), Erysimum (wallflower), Hesperis 

matronalis (rocket), Iberis sempervirens (candytuft), 

Lobularia maritima (sweet alyssum), Lunaria annua 

96 

(honesty, money plant), Matthiola (stock); dye: Isatis 

tinctoria (dyer’s woad); endangered: Cardamine diphylla 

(two-leaved toothwort), C. dissecta (divided 

toothwort). 

Alliaria petiolata (garlic mustard) is the scourge of the 

forest, replacing native wildflowers by shading them out 

of existence. As a biennial, it produces a rosette of 

leaves the first year, and flowers and seeds the second 

year, then dies. One plant can produce several thousand 

seeds that are viable for seven years or more. 

Garlic mustard eliminates native food plants for native 

animals. In state parks overrun with garlic mustard, it 

is not unusual to see deer begging for edible handouts 

from tourists. 

Lobularia maritima Sweet Alyssum 

A native of the Mediterranean area, this plant is an annual 

or perennial herb. The leaves (a) are linear and 

alternate to almost opposite on the stem (b). The habit 

drawing shows the pedicelled flowers (c), borne on a 

stalk (raceme) and the silicle (d) fruit. 

The pedicel (e) supports a flower with 4 hairy 

sepals (f) that alternate with the 4, diagonally opposed 

petals (g). The 6 stamens are tetradynamous, which 

means there are 4 long stamens (h) and 2 outer short 

stamens (i). At the base of the filament are nectaries 

(j), seen when the sepals and petals are removed. 

The single pistil has a superior ovary (k) and a capitate 

stigma (l). When the silicle fruit develops. the ovary’s 

false partition (replum, m) can be seen separating the 

seeds (n). Two outer valves (o) are shed to release the 

seeds. 

COLOR CODE 

green: leaves (a), stem (b), pedicel (e), 

sepals (f) 

white or lavender: flowers (c), petals(g) 

yellow: silicle (d), stamens (h, i), replum 

(m), valves (o) 

pale green: nectaries (j), ovary (k), stigma (l) 

tan: seeds (n)

Heath Family (Ericaceae) 

Shrubs are the most common in this family, but some 

plants are perennial herbs, trees, or vines. Most prefer 

acidic substrate and many have fungus-root (mycorrhizal) 

associations (see 12). Leaves are simple, alternate, 

sometimes opposite or whorled, and often leathery 

and evergreen. There are about 100 genera and 

about 3,000 species. 

Flowers are bisexual, borne, singly or in clusters. The 

4-5 sepals are distinct or joined at the base. There are 

usually 4-5 petals joined in a funnel or urn-shape, but in 

some genera, the petals are separate. Stamens are the 

same or twice the number of petals. The single pistil has 

a superior ovary of 4-10 carpels with ovules usually in 

axile placentation, and a single style and stigma. Fruit 

types (see 38, 39) include capsules, berries, or drupes. 

Of interest...food: Gaultheria procumbens (oil-ofwintergreen), 

Gaylussacia (huckleberry), Vaccinium 

spp. (bilberry, blueberry, cranberry, lingonberry); ornamentals: 

Calluna (heather), Enkianthus campanulatus 

(redvein enkianthus), Kalmia latifolia (mountain 

laurel), Leucothoe catesbii (leatherleaf), Oxydendrum 

arboreum (sourwood), Pieris japonica (andromeda), 

Rhododendron spp. (rhododendron, azalea); wild: 

Arctostaphylos (bearberry), Epigaea repens (trailing 

arbutus); poisonous: Andromeda glaucophylla (bog 

rosemary), Kalmia angustifolia (lamb-kill), K. latifolia 

(mountain laurel), K. polifolia (swamp laurel), Leucothoe 

spp., Lyonia mariana (stagger-bush), Menziesia ferruginea 

(fool’s huckleberry), Rhododendron spp. It is advised 

not to roast food on sticks of any of the plants 

listed. 

Here is how to tell a rhododendron from an azalea. 

Although they share the same genus (Rhododendron), 

97 

rhododendron flowers have 10 stamens while azalea 

flowers have 5 stamens. Rhododendrons are 

mostly evergreen plants, while azaleas are mostly 

deciduous. 

Arctostaphylos uva-ursi Bearberry, Kinnikinik 

This plant forms mats of prostrate shrubs, cloned by 

shoots arising from the root system. The alternate leathery 

leaves (a) are evergreen. Young stems (b) and 

leaf blade margins and petioles are covered with fine 

hairs. 

Urn-shaped flowers are borne in small clusters at the 

end of the shoot. The flower has 5 basally fused, pink 

sepals (c), a fused petal tube (d) with 5 lobes (e), 

10 stamens, and a single pistil with a superior ovary. 

The stamen’s anther (f) has 2 cells each with a pore 

(g) for pollen dispersal and a bristly awn (h) at the 

base of each. The stamen’s filament (i) is dilated at the 

base. 

The pistil’s ovary (j) has 5-8 chambers (locules) with 

one ovule (k) in each, in axile placentation. The pistil 

has a single columnar style (l) and stigma (m). The 

ovary is elevated on a 2-lobed nectar disc (n). Hairs (o) 

line the inner surface of the petal tube and cover the 

stamen’s dilated filament base. 

As the drupe (r) type fruit matures, the skin color 

changes from yellow to red, then to purple as it decays. 

Inside is a fleshy mesocarp (s) surrounding 

the fused nutlets (t). Yellow veins (u) run as a band 

along the back of each and as seams between the 

nutlets. 

COLOR CODE 

green: leaves (a), disc (n) 

brown: stem (b) 

dark pink: sepals (c), petal lobes (e) 

pale yellow: petal tube (d), mesocarp (s), vein (u) 

purple: anther (f) 

pink: awn (h) 

red-brown: pedicel (p), bract (q) 

red: drupe (r) 

tan: nutlet (t) 

white: filament (i), ovary (j), ovule (k), 

style (l), stigma (m)

Saxifrage Family (Saxifragaceae) 

Distinctive characteristics to identify this family are 

lacking. The flower parts tend to be in 4’s or 5’s with 

stamens one or two times the number of sepals and 

with a pistil consisting of 2-5 united carpels having numerous 

ovules. 

The leaves are mostly without stipules and usually alternate 

on these commonly perennial herbs and deciduous 

shrubs. The fruit type is a capsule or berry. 

Of interest...food: Ribes spp. (gooseberry, currant); 

ornamentals: Astilbe (false goat’s-beard), 

Bergenia cordifolia (pigsqueak), Darmera, Deutzia, 

× Heucherella (Heuchera × Tiarella), Heuchera (coral 

bells), Hydrangea, Mukdenia, Philadelphus (mock orange), 

Rodgersia (Roger’s flower), Saxifraga spp. 

(saxifrages), S. stolonifera (see 16, strawberry begonia, 

Aaron’s-beard, mother-of-thousands); wild: Mitella 

(bishop’s-cap), Tiarella (foamflower, false miterwort). 

Ribes americanum Wild Black Currant 

This shrub has alternate leaves (a) with yellow resin 

dots (b) on the lower surface of the blades. 

Small flowers (d) have 5 petal-like sepals (e), 5 petals 

(f), and 5 stamens (g). The single pistil has an inferior 

ovary (h) of 2 united carpels with ovules (i) in parietal 

placentation, and a style (j) that divides into 2 stigmas 

(k). 

Heuchera sanguinea Coral Bells 

This perennial herb has basal leaves (m) and develops 

flowering shoots on long peduncles (n). The peduncle 

is green at the base and fades into dark pink at the 

top where the flowers occur. Like Ribes, the 5 sepals 

(p) are united at the base and petal-like. With magnification, 

delicate, pink, glandular hairs can be seen on 

the sepals. Inside the sepal tube are 5 tiny petals (q), 

5 stamens (r) and a pistil with 2 stigmas. 

Philadelphus Mock Orange 

This deciduous shrub has opposite leaves and flowers 

that have the fragrance of orange blossoms and produce 

loculicidal capsules (s). 

98 

COLOR CODE 

yellow: resin dots (b), stamens (g, r) 

green: leaves (a, c, m) pedicel (l), peduncle (n) 

pale yellow: flowers (d), sepals (e), petals (f) 

white: ovary (h), ovules (i), style (j), stigmas (k) 

pale pink: petals (q), upper portion of peduncle (n) 

dark pink: pedicel (o), sepals (p) 

tan: capsule (s), stem (t)

Rose Family (Rosaceae) 

Common features in this family include the following: 

leaf stipules are usually present, flower parts are in 5’s 

and the flower has a cup-like receptacle or floral tube, 

called a hypanthium, which develops around the ovary. 

Plants in the rose family range from herbs and shrubs 

to trees. Many have spines and a few are climbers. Usually, 

the leaves are alternate, simple or compound, with 

toothed (dentate) margins. The flower is usually bisexual 

and has an enlarged nectar cup that inflates the floral 

tube, has stamens in whorls of five, and possesses 

a single compound pistil or many pistils together. 

There are over 3,000 species in the Rose Family. 

Of interest...fruit types: achene, drupe, follicle and 

pome. Rose family plants have English common names 

for the edible fruits. In combination with the fruit 

type, some examples follow. Strawberry (Fragaria) is 

an aggregate of achenes. Pear (Pryus), apple (Malus), 

and quince (Cydonia) are pomes. Cherry (Prunus 

avium), peach (Prunus persica), plum (Prunus spp.) 

and apricot (Prunus armeniaca) are drupes. Blackberry 

(Rubus ulmifolius), raspberry (Prunus idaeus), loganberry 

(Prunus loganobaccus), dewberry (Rubus caesius) 

and cloudberry (Rubus chamaemorus) are aggregates 

of drupelets. The fleshy fruit of the almond 

(Prunus dulcis) is not eaten; the common name represents 

the seed inside the drupe’s pit, while a similar 

appearing seed in the peach drupe contains a poison, 

cyanide, as do the pome seeds of apple (Malus). 

Ornamental shrubs whose fruits are not usually eaten 

are named for other characteristics. Named for thorns, 

hawthorn (Crataegus) and firethorn (Pyracantha) have 

pome fruits. Bridal wreath (Spiraea) is cultivated for 

its sprays of white flowers and has a follicle fruit, as 

does ninebark (Physocarpus). Mountain ash (Sorbus), 

with a pome fruit, has compound leaves similar to 

those of ash (Fraxinus) in the olive family. Roses (Rosa 

spp.) are cultivated for their showy flowers, which are 

edible (candied rose buds) and develop into “hips” 

composed of many carpels, which form an aggregate 

of achenes high in vitamin C. Other ornamental 

shrubs are Amelanchier (with many common names: 

Juneberry, serviceberry, shadblow, shadbush), Aronia 

(chokeberry), and Kerria japonica from China. Some 

99 

ornamental herbaceous perennials include lady’s 

mantle (Alchemilla), goatsbeard (Aruncus), meadowsweet 

(Filipendula), avens (Geum), cinquefoil (Potentilla), 

and burnet (Sanguisorba). 

Malus pumila Apple 

This is a tree of spreading branches. The stems (a) have 

characteristic short, spur shoots (b) that bear leaves, 

flowers, and fruits. Small stipules (d) occur at the petiole 

base. 

The flower has 5 basally joined sepals (e) and 5 petals, 

which are white above and pink below (f). In bud (g), the 

flowers appear pink. When the flower opens, the petals 

appear white and are blushed pink from the recurved 

tips. There are many stamens (h) in whorls of 5. 

The vertical section shows the stamens (j) attached to 

the floral tube (k) outside the nectar cup (l). The pistil 

has an inferior ovary (m) with 5 carpels (n) and a style 

(o) that projects through the nectar cup and divides into 

5 branches topped with stigmas (p). 

The cross-section of an ovary shows the floral tube 

tissue (k), carpellary tissue (q) and ovules (r) in the 

5 carpels. Other features are vascular bundles of the 

carpels (s), petals (t), and sepals (u). A hairy epidermis 

(v) covers the floral tube. 

The cross and vertical sections of a pome show how 

the structures of a small flower develop into a fruit 

after fertilization. The ovules develop into seeds (w) in 

the carpels (n). Carpellary tissue (q) enlarges, the floral 

tube tissue (k) expands, and the epidermis (x) becomes 

pigmented (yellow, red, or green). 

COLOR CODE 

brown: stem (a), short shoot (b), seeds (w) 

green: leaves (c), stipules (d), sepals (e), 

peduncle (i), sepal bundles (u), 

epidermis (v) 

pink: lower surface of petals (f), bud (g) 

yellow: stamens (h, j) 

white: floral tube tissue (k), nectar cup (l), 

carpels (n) 

light green: stigmas (p), petal bundles (t) 

red: epidermis (x) 

pale yellow: carpellary tissue (q), ovules (r), carpel 

bundles (s)

Pea Family (Fabaceae) 

The old family name was Leguminosae, a reference to 

the legume fruit (see 38). Members of this family are 

easily recognized by the usually alternate, compound 

leaves divided into leaflets, the typical pea flower, and 

the pea pod (legume) fruit. The form of plants ranges 

from small herbs to shrubs and trees. There are 700 

genera and over 17,000 species. 

Looking closely at the leaves, the base of each has a 

pair of leaf-like stipules. The leaf petiole has a swollen 

base (pulvinus) that has the ability to change the 

position of the leaf and leaflets when stimulated by 

light or gravity. When touched, Mimosa, the sensitive 

plant, demonstrates this ability, dramatically (movement 

occurs rapidly). 

A pea flower has 5 fused sepals, with 5 separate petals 

or petals in 3 groups of one banner petal, two wing 

petals, and a keel of 2 fused petals that enclose the 

stamens after fertilization. The ovules are attached to 

the side of the carpel wall in two alternating rows. 

Some species have only two seeds per legume pod; 

others may have many. Pods may be straight such as 

in garden beans and peas, or straight and sectioned 

into compartments called a loment, or coiled in a spiral 

(see 38). When mature, the pod splits into halves. 

Pea family plants such as clover or alfalfa are often used 

in crop rotation because they increase soil nitrogen, a 

plant nutrient, by the presence of bacterial nitrogenfixing 

nodules on the roots (see 12). 

Of interest...economically important for food: Arachis 

(peanut), Cicer (chick pea), Glycine max (soybean), 

Lens (lentil), swollen roots of Pachyrhizus erosus 

(jicama), Phaseolus spp. (beans), Pisum (pea), 

Tamarindus (tamarind), Vicia faba (broad bean, fava 

bean), Vigna angularis (adzuki bean); native American 

foods: tubers of Apios americana (ground nut), 

tubers of Psoralea esculenta (prairie potato); fodder: 

Lupinus (lupine), Medicago (alfalfa), Melilotus (sweet 

clover), Prosopsis juliflora (Mexican mesquite tree pods 

and beans), Trifolium (clover, see 33), Vicia (vetch); ornamentals: 

Acacia (wattle), Albizzia, Baptisia (false indigo), 

Bauhinia (orchid tree), Caesalpinia pulcherrima 

(pride of Barbados), Cassis (senna), Cercis (redbud), 

Cytisus scoparius (Scotch broom), Delonix (poinciana), 

Genista, Gleditsia (honey locust), Laburnum (goldenchain 

tree), Lathyrus (sweet pea), Lupinus (lupine), 

100 

Mimosa (sensitive plant), Wisteria (wisteria); dye 

plants: Genista tinctoria (yellow dye), Indigofera (indigo); 

poisonous: Abrus precatorius (precatory bean), 

Astragalus (locoweed), Gymnocladus (Kentucky coffee 

tree), Lupinus argenteus (silvery lupine), Robinia (locust); 

invasive weeds: introduced to the United States 

for erosion control, Coronilla varia (crown vetch) is now 

an invasive plant overrunning natural prairies and savannas; 

Pueraria montana (kudzu vine, “the vine that 

ate the south.”) 

Lathyrus latifolius Sweet Pea 

A perennial herb, the sweet pea plant climbs by means 

of tendrils (a) on its broadly winged stems (b). Doublelobed 

stipules (c) emerge from nodes on the stem. The 

compound leaf has a winged petiole (d) and two leaflets 

(e). 

The raceme inflorescence has a long peduncle (f) that 

supports many flowers on short pedicels (g). In addition 

to a sepal tube (h) with 5 lobes, the flower has a corolla 

divided into a banner petal (i), 2 wing petals (j), and a 

keel (k) composed of 2 fused petals. Petal color varies 

from white to pink to dark pink-red. 

With the petals removed from a flower bud, 10 

2-chambered stamens (l) enclose the pistil in 2 bundles 

of one above plus nine basally fused ones. A 

flower, with sepals (h) also removed, and ovary (m), cut 

open, shows the ovules (n) attached to the inner carpel 

wall. Extending from the ovary are the style (o) and 

stigma (p). 

When the sweet pea legume (q) matures, the carpel 

wall splits into two halves and twists, thus expelling the 

seeds(r). 

COLOR CODE 

green: tendril (a), stem (b), stipules (c), 

petiole (d), leaflets (e), peduncle (f), 

pedicel (g), sepals (h) 

white, pink, or 

pink-red: petals (i, j, k) 

yellow: stamens (l) 

light green: ovary (m), ovules (n), style (o), 

stigma (p) 

tan: legume (q) 

dark brown: seeds (r)

Dogwood Family (Cornaceae) 

Plants in this family are usually woody trees and shrubs 

with simple, usually opposite leaves. The small flowers 

are arranged in clusters that are sometimes subtended 

by bracts that may be quite showy. The flower is bisexual 

or has unisexual male and female flowers on one 

plant (monoecious) or on separate plants (dioecious). 

There are about 13 genera and over 100 species. 

Attached to the ovary are 4–5 sepals and 4–5 petals 

or none. The number of stamens is the same as the 

number of petals. There is a single pistil with an inferior 

ovary consisting of 2–4 carpels. A glandular disc 

surrounds the one or more styles. Fruits are drupes or 

berries. 

Of interest...ornamentals: Acuba (Japanese laurel), 

Cornus canadensis (bunchberry), C. florida (flowering 

dogwood), C. sericea (red-osier dogwood), C. mas 

(Cornelian cherry), C. kousa (Japanese dogwood), 

C. racemosa (grey dogwood), Griselinia spp. (kapuka), 

Helwingia. 

Cornus florida variety rubra 

Flowering Dogwood 

This small tree has widely spreading branches and is 

valued as an ornamental specimen tree in landscaping. 

In nature, this understory tree of the forest has white 

flowers. Mutant pink and red varieties have been selected 

from natural populations of flowering dogwood 

and propagated for horticultural use. 

The opposite leaves are simple with entire, wavy margins. 

In autumn they turn a deep red color. 

What appear to be pink flower petals are actually 4 large 

bracts (b) around a cluster of 20-30 bisexual flowers (c) 

with yellow petals. Each flower has 4 joined sepals (d), 

4 small petals (e, f), 4 stamens (g), and a single pistil 

(h). The stamens arise from the base of a nectar disc 

(k). Parts of the pistil include a 2-carpelled ovary (l) with 

an ovule (m) in each locule, a style (n), and stigma (o). 

Birds are very fond of the bright red drupe fruits (p). 

101 

COLOR CODE 

dark pink: bract veins (a) 

pink: bracts (b) 

yellow-green: flowers (c), bud petals (e) 

light green-pink: sepals (d) 

white: filament (j), ovary (l), ovules (m) 

yellow: petals (f), stamens (g), anther (i), 

nectar disc (k) 

light green: pistil (h), style (n), stigma (o) 

red: drupes (p) 

gray: peduncle (q) 

optional: leaf (green in summer; or dark red 

with yellow veins in autumn)

Staff-tree Family (Celastraceae) 

The most obvious characteristic this family is the pulpy 

orange or red aril usually covering the seed. Small clusters 

of green flowers usually have flower parts in 4’s 

or 5’s. The flowers are bisexual or sometimes polygamodioecious 

(see Celastrus, below). There is one 

pistil with a superior ovary surrounded by a nectar disc. 

Plants in this family are woody shrubs, trees, and twining 

vines. Leaves are simple, alternate or opposite. 

There are 55 genera and 850 species. 

Of interest...ornamentals: Catha (Cafta), Celastrus 

(bittersweet), Elaeodendron, Euonymus alatus 

(burning bush), Gymnosporia, Maytenus, Pachystima, 

Tripterygium; furniture making: Euonymus europaeus 

(European spindle tree); food: Catha edulis (Khat tree), 

leaves for tea. 

Euonymus alatus Burning Bush, 

Winged Wahoo 

This shrub’s stems (a) have a winged appearance because 

of the presence of corky ridges (b) of periderm. 

Its opposite leaves (c) have finely toothed (dentate) 

margins and hair-like stipules (d) at the base of the petioles. 

In autumn, the leaves are a brilliant red. 

The flowers are borne in a cluster, with the central 

flower opening first (cyme). Parts of the bisexual flower 

consist of 4 sepals (e), 4 petals (f), and 4 stamens 

(g) surrounding the single pistil (h) with 4 carpels (i). 

102 

Stamens and pistil are situated on a disc (j), which is 

a fleshy receptacle with the sepals and petals arising 

around it. 

After the leaves are shed in autumn, the loculicidal 

capsule (m) is more obvious. A red outer covering (aril, 

n) encloses the seeds. 

This vigorous growing native of the Temperate Zone in 

East Asia can crowd out plants that are native to the 

American Temperate Zone because of its prodigious 

seed production and high seedling survival rate. 

Celastrus scandens Bittersweet 

Bittersweet is a twining vine with alternate leaves (o). 

Polygamodioecious is the condition describing the 

plants’ flowers. This means that unisexual male and female 

flowers are mainly on separate plants, but bisexual 

flowers are also present on both plants. 

The male flower consists of 5 sepals (r), 5 petals (s), 5 

stamens (t), and a vestigial pistil (u). The female flower 

(not shown) has a pistil composed of 3 carpels, a single 

style, and a 3-lobed stigma with vestigial stamens 

present. 

The fruit type is a loculicidal capsule. Three orange 

valves (v) open to expose a red aril (w) covering the 

seeds. Autumn branches of orange fruits are used for 

decoration. 

COLOR CODE 

brown: bark ridges (b) 

green: stem (a, p), leaves (c, o), stamens (g), 

pistil (h), carpels (i), pedicel (k, q), 

disc (j), pedicel (k, q), 

light green: sepals (e, r), petals (s) 

yellow-green: petals (f) 

pink: pedicel (l) 

lavender: capsules’ valves (m) 

orange: capsules’ valves (v) 

red: arils (n, w) 

yellow: pedicel (x), stamens (t) 

white: pistil (u)

Spurge Family (Euphorbiaceae) 

Euphorbs, a large family of 283 genera, often have 

a poisonous, milky, latex sap. Very diverse forms are 

represented. There are weedy herbs, commonly called 

spurges, showy ornamental herbs, trees, and cactuslike 

succulents. Most are tropical. Stems usually have 

stipules that take the form of hairs, glands, or spines. 

False flowers, often with petal-like appendages, have 

unisexual, male and female flowers aggregated in a 

cyanthium (a cup-like structure). Male flowers, of one 

stamen each, may number 1 to many in a cyanthium. 

The female flower is a single pistil composed of a superior 

ovary with usually 3 fused carpels, 3 styles, and 

3-6 stigmas. The fruit is usually a schizocarp in which 

the three carpels, bearing seeds, break apart. 

Of interest...economic: Aleurites fordii (tung oil, used 

in paints and quick-drying varnishes), Hevea brasiliensis 

(para rubber, the most important source of natural 

rubber), Manihot esculenta (tapioca, bitter cassava, 

manioc, sweet-potato tree; the starchy roots 

yield many food products), M. glaziovii (ceara rubber), 

Ricinus communis (castor oil); ornamentals: Acalpha 

hispida (chenille plant), Codiaeum (croton), Euphorbia 

with 1550 species (poinsettia, crown-of-thorns, 

spurges), Pedilanthus tithymaloides (redbird flower, 

slipper flower, redbird cactus, Japanese poinsettia), 

Phyllanthus (Otaheite gooseberry, gooseberry tree), 

Ricinus communis (castor-bean). 

poisonous: Aleurites fordii (tung oil), Euphorbia spp., 

The milky sap of Euphorbia species causes dermatitis 

with severe blistering on contact with human skin, 

103 

E. marginata (snow-on-the-mountain, ghostweed), a 

garden ornamental, is especially corrosive to the skin; 

Ricinus communis (castor-bean, castor-oil-plant) contains 

ricin, a blood poison. All parts of the plant are poisonous, 

but particularly the “bean” (seeds). If ingested 

severe poisoning, ending in convulsions and death, can 

occur. 

Euphorbia milii Crown-of-thorns 

This native of Madagascar is a spiny, succulent 

shrub. The stem (a) has alternate, simple leaves (b), 

spiny stipules (c), and latex sap (d). Two flowering 

shoots (e) are shown, one with the petal-like appendages 

(f) in bud and the other with the appendages 

expanded (g). 

The drawing shows an enlarged false flower, called a 

pseudanthium, has five nectar glands (h) and 5 bracts 

(i) that surround the flowers. At the center of each of 

the female flowers are 3 styles (j), which divide into 2 

stigmas (k). With the petaloid appendages removed, 

the cyanthium can be seen. Male flowers (l), three are 

complete in the illustration, develop before the female 

flower. 

The female flower, in an enlarged drawing, shows 

the ovary’s 3 fused carpels (o), which contain ovules 

in axile placentation, the styles, and stigmas. The 

ovary develops into a schizocarp (p) fruit, which 

has green petaloid appendages (q) in this related 

species. 

COLOR CODE 

green: stem (a), leaves (b), peduncle (e), 

nectar glands (h), pedicel (m, n), 

petal-like appendages (q) 

gray: stipules (c) 

white: latex (d) 

red: petal-like appendages (f, g) 

yellow: bracts (i), male flowers (l) 

light green: style (j), stigma (k), ovary (o) 

tan: schizocarp (p)

Grape Family (Vitaceae) 

This family consists mostly of climbing vines with tendrils 

that develop opposite the leaves. The tendrils 

may be twining, as in grape (Vitis), or end in attaching 

discs (see 16), as in Virginia creeper (Parthenocissus). 

Flower clusters also develop at the node opposite a 

leaf. The leaves are alternate, simple or pinnately or 

palmately compound. There are twelve genera and 

about 700 species. 

The minute flowers are bisexual or unisexual on the 

same plant (monoecious). Usually there are 4–7 

sepals, 4–7 petals, 4–7 stamens, and a single pistil, 

which develops into a berry fruit. 

Of interest...food: Vitis spp. (grape berries are 

used for making wine and jellies; dried gapes for 

raisins and currants); ornamentals: Cissus spp. (grape 

ivy), Parthenocissus quinquefolia (Virginia creeper), 

P. tricuspidata (Boston ivy). 

Vitis riparia River-bank Grape 

Lobed leaves (a) with palmate venation are alternate 

to each other and opposite tendrils (b) on the stem (c). 

Tiny, unisexual, male and female flowers occur on this 

plant. 

Above the flower pedicel (d) joined sepals (e) appear as 

a wavy-margined cup in bud. The flower is covered with 

petals (f) joined at the top. As the petals separate into 

5-6 lobes (g), the stamens’ filaments (h) and the nectar 

disc (i) are exposed. When the petal cap is shed, the 

5-6 anthers (j) can be seen. 

The female flower, with the petal cap shed, consists of 

sepal cup (k), nectar disc (l), and pistil composed of 

a superior ovary (m) and a short style with a capitate 

(formed like a head) stigma (n). 

Clusters of female flowers develop into the familiar 

bunch of grapes, botanically called berries (o, p). 

104 

COLOR CODE 

green: leaves (a), stem (c), pedicels (d), 

sepal cup (e), peduncle (q), 

underdeveloped berrry (p) 

red: tendril (b) 

light green: petals (f, g), ovary (m), stigma (n) 

dark green: nectar disc (i, l) 

white: filaments (h) 

yellow: anthers (j) 

purple: sepal cup (k) 

dark blue: berries (o)

Maple Family (Aceraceae) 

Maples have opposite branches and leaves. The leaves 

may be simple, with palmate venation, or compound as 

in box elder (Acer negundo, see 35). Species differ in 

leaf shape with margins entire or variously toothed or 

variously lobed. The two genera (Diperonia from China 

and Acer) in this family are small to large deciduous 

trees found mainly in the North Temperate Zone. 

The flower in some species is bisexual, but usually 

it is unisexual with both male and female flowers on 

the same tree (monoecious) or separated on different 

trees (dioecious). Unisexual flowers may have vestigial 

organs of the opposite sex. There are usually 5 

sepals, 5 petals or none, 4–12 stamens, and a single 

pistil with a superior ovary. The 2 fused carpels of the 

ovary develop into a double samara fruit. 

Of interest...lumber: Acer saccharum (sugar maple), 

A. macrophyllum (big leaf maple); food: A. saccharum 

(sugar maple, all maple species yield sap with 

a high sugar content); ornamentals: A. saccharum 

(sugar maple), A. platanoides (Norway maple), A. pseudoplatanus 

(sycamore maple), A. ginnala (amur maple), 

A. palmatum (Japanese maple) with many cultivars for 

variously cut leaves and colors. 

Acer saccharinum Silver Maple 

This maple tree grows to 37 meters high. The main trunk 

divides near the ground into several upright stems. It is 

105 

a fast-growing tree with narrow-angled brittle branches 

and a spreading root system. Therefore, it should not 

be used for landscaping, even though many people use 

it for this purpose by mistake. 

Opposite leaves (a) are 5-lobed with palmate venation 

(b) and toothed (dentate) margins. The leaf is green on 

the upper surface and silvery on the lower surface (c). In 

one location with two silver maple trees growing next to 

each other, the tree bearing male flowers in the spring 

produces yellow autumn leaves, while the other tree 

bearing female flowers in the spring has red autumn 

leaves. 

This species is dioecious and wind-pollinated, with 

flowers opening before the leaves (e) expand on the 

stem (f). Hair-fringed bud scales (g) enclose clusters 

of male flowers (h). The male flower has joined sepals 

(i), a variable number of stamens (j), and a vestigial 

pistil (k). 

Clusters of female flowers (l) are produced on another 

tree. The female flower consists of a sepal cup (m) 

and vestigial stamens (n), and the single pistil has an 

ovary consisting of 2 fused carpels (o) and 2 plumose 

(feathery) stigmas (p). Two ovules occur in each carpel, 

but only one develops, so that the fruit is a double 

samara (q) with a seed (r) on each side. In suitable soil, 

there is almost 100% germination of the seeds, another 

good reason not to use this plant in the landscape. 

COLOR CODE 

yellow: autumn leaves (a), male flowers (h), 

stamens (j, n) 

green: veins (b), leaf bud (e), stem (f), 

female flowers (l), stigmas (p) 

white: leaf lower surface (c), pistil (k), 

carpels (o) 

brown: stem (d), samara (q, r) 

red: bud scales (g) 

pale yellow: sepals (i, m)

Cashew Family (Anacardiaceae) 

Plants in this family usually have resin ducts in the 

tissues. The resin in some of these plants causes contact 

dermatitis in humans. Poison ivy, poison oak, and 

poison sumac are familiar examples. 

Trees, shrubs, and vines, with usually alternate and 

compound leaves, are present in this family. The small 

flowers form in branched clusters (panicles) and are 

bisexual or unisexual. Flower features are a prominent 

nectar disc and a pistil of fused carpels that form one 

seed cavity in which one ovule develops. Fruits are usually 

drupes. There are about 80 genera and about 600 

species. 

Of interest...food: Anacardium occidentale (cashew), 

Mangifera indica (mango), Pistacia vera (pistachio); 

resins: Pistacia lentiscus (mastic tree), Toxicodendron 

vernicifera (varnish tree); tannic acid: Rhus typhina 

(staghorn sumac), Schinopsis; ornamentals: Cotinus 

coggygria (smoke tree), Rhus aromatica (fragrant 

sumac), Rhus copallina (shining sumac), R. typhina 

‘Laciniata’ (lacy-leafed staghorn sumac); poisonous: 

Metopium toxiferum (poison-wood, doctor gum coralsumac), 

Toxicodendron verniciflua (Japanese lacquertree), 

T. radicans (poison-ivy, poison-oak), T. diversiloba 

(Pacific poison-oak), T. vernix (poison-sumac). 

Rhus typhina Staghorn Sumac 

An extensive clone of shrubs may be formed from one 

plant by new shoots arising from the root system. The 

106 

common name refers to the very hairy stem that has 

the appearance of new antlers. The leaves are alternate 

and compound, with opposite pairs of leaflets (a) on the 

petiole (b). In autumn, leaves become a brilliant red. 

In the spring, clusters of flowers form at the ends of 

shoots. An individual plant has either male or female 

flowers with vestigial organs of the opposite sex. The 

male flower has 5 sepals (c), 5 petals (d), 5 stamens 

(e), and a vestigial pistil (f). Staminal filaments (g) arise 

beneath the nectar disc (h). 

The female flower has 5 sepals (j), 5 petals (k), 5 

vestigial stamens (l) and a single pistil with 3 stigmas 

(m). Arising from the nectar disc (n), the superior 

ovary (o) consists of three fused carpels containing one 

ovule. 

In autumn, plants with female flowers produce conspicuous 

upright clusters of drupes (p) on the ends 

of shoots. The drupe’s epidermis is covered with red 

hairs (q). When partially removed, a single seed (r) is 

exposed. 

Cotinus coggygria Smoke Tree 

In late summer, this low structured tree is covered with 

what appears to be clouds of pink smoke. As the drupes 

(s) form, the surrounding hairy, filamentous stems (t) 

change from green to pink. 

COLOR CODE 

red: petiole (b) 

green: leaflets (a), sepals (c, j), pedicel (i), 

leaf (u) 

yellow: anthers (e) 

white: pistil (f), filaments (g) 

light green: petals (d, k), stigmas (m), ovary (o), 

anthers (l) 

orange: nectar disc (h, n) 

dark red: drupes (p), hairs (q) 

tan: seed (r) 

brown: drupes (s) 

pale pink: stems (t)

Rue Family (Rutaceae) 

Aromatic essential oils are produced in glands that 

appear as clear “dots” on the leaves. Another characteristic 

feature of this family is that within the usually 

bisexual flowers, the pistil has a superior, usually lobed 

ovary situated on a nectar disc. 

Rue family plants include trees, shrubs, and herbs, 

with many different fruit types represented. They include 

capsules, leather-rind berries (hesperidia), drupes, 

and samaras. There are 150 genera and about 

900 species. 

Of interest...food: Citrus 60 species, with many 

hybrids between species, Citrus sinensis (sweet 

orange), C. limon (lemon), C. paradisi (grapefruit), C. 

aurantifolia (lime), C. aurantium (Seville orange), C. 

reticulata (tangerine, manderin, satsuma), C. medica 

(citron), Fortunella (kumquat), Pummelo; ornamentals: 

Calodendrum (Cape chestnut), Choisya ternata, 

Dictamnus (gas plant, fraxinella, dittany), Diosma, Murraya 

(orange jessamine), Phellodendron spp. (“cork” 

trees), Poncirus (trifoliate orange), Ptelea (hop tree, 

wafer ash), Ruta graveolens (common rue), Skimmia, 

Zanthoxylum americanum (prickly ash); lumber: 

Zanthoxylum flavum (West Indian silkwood); poisonous: 

Dictamnus, Ruta graveolens, Ptelea. 

Citus limon Lemon 

The small lemon tree has alternate, simple leaves (a) 

with translucent glands containing aromatic oil. Citrus 

107 

species’ leaves have various sizes of petiole wings (b). 

A grapefruit (C. paradisi) leaf (c) is shown for comparison 

of the winged petiole (d). 

Small, bisexual flowers, produced in clusters, are very 

fragrant. The 5 joined sepals (f) form a cup. Inside the 

cup are 5 petals (g) and many stamens (h) of unequal 

lengths. Some of the filaments (i) are joined together, 

and arise at the base of the nectar disc (j). 

The pistil is situated in the center of the disc surrounded 

by the stamens, with the stigma (k) at anther (l, m) level. 

The pistil has a superior ovary (o), a single style (p) 

composed of fused canals leading to the carpels, and 

a single stigma (q). As the fruit (r) develops, the petals, 

stamens, and the style are shed. 

The fruit is a berry with a leathery rind (hesperidium). 

The rind or exocarp(s) has oil glands. Inside the rind is 

the spongy mesocarp tissue (t). Inside the mesocarp 

is the endocarp, which produces the juice sacs (u) of 

enlarged cells. 

The seed (v) contains a green chlorophyll-containing 

embryo, which may germinate within the fruit. This is 

called vivipary. The grapefruit leaf shown here is from 

a plant that was grown from a seed that germinated 

within a fruit. 

COLOR CODE 

green: leaf blade (a, c) petiole wings (b, d), 

peduncle (n), nectar disc (j), ovary (o), 

fruit (r) 

light green: pedicel (e), sepal cup (f), stigma (k) 

white: petals (g), stamens (h), filaments (i), 

style (p), mesocarp (t) seeds (v) 

yellow: anthers (l, m), exocarp (s), juice sacs (u) 

tan: stigma (q)

Geranium Family (Geraniaceae) 

Mostly herbs and some small shrubs are represented 

in this family. Scented leaves in some species, a flower 

with parts in 5’s, and a beaked or lobed fruit are some of 

the characteristics. There are eleven genera and about 

750 species. 

Leaves are alternate or opposite, and compound or simple 

with lobes or divisions. They usually have palmate 

venation and stipules. Usually in clusters, the bisexual 

flower has 5–15 stamens in whorls of 5 and a single pistil 

with 3–5 carpels in a superior ovary. Adhering to the 

ovary axis, the 3–5 styles aid in an unusual seed dispersal 

mechanism. The fruit is a septicidal or loculicidal 

capsule. 

Of interest...ornamentals: Erodium spp. (stork’sbill, 

heron’s-bill), Geranium spp. (hardy geraniums, 

400 species). Some popular garden geraniums are 

G. cantabrigiense ‘Biokovo’, G. cinereum ‘Ballerina,’ 

G. himalayense × G. pratense ‘Johnson’s Blue,’ G. 

‘Rozanne,’ G. sanguineum, G. macrorrhizum, G. × 

magnificum. Pelargonium zonale is the geranium of 

commerce and native to South Africa. Some with 

scented leaves include P. crispus (lemon-scented), 

P. graveolens (rose-scented), P. fulgidum (spicescented), 

P. tomentosum (peppermint-scented). 

Geranium maculatum Wild Geranium, 

Crane’s-bill 

This spring-flowering herb produces annual shoots 

from a thick perennial rhizome. Leaves (a) at the base of 

108 

the plant have 5–7 lobes and long petioles (b), while upper 

leaves (c) have 5 lobes and shortened petioles (d). 

The leaves have stipules (f) and palmate venation. 

Flowers form in a flat-topped cluster with the central 

flower opening first (cyme). The flower has 5 persistent 

sepals (j) with spine-like tips (k), which are clearly seen 

when the petals are removed. Five lavender petals (l) 

have green veins (m). 

The 10 stamens (n) are in two whorls of 5 each around 

the base of the pistil (o). Staminal filaments (p) are attached 

at the center of the anther (q) and flare outward 

at the bases. In the illustration, the anthers of 

the inner whorl of stamens are open, exposing pollen 

grains, while the anthers of the outer whorl are not yet 

mature. 

The single pistil has a superior ovary (r) of 5 fused 

carpels (s), 5 styles (t), which form a column around 

the ovary axis (u), and 5 stigmas (v). Between the petal 

bases are 5 nectar glands (w). 

Crane’s-bill, one of the common names, applies to the 

fruit, a beaked, septicidal capsule. At the time of seed 

dispersal, the styles (t, x) attached to the carpels (s, y) 

coil elastically, which propels the seeds (z) out of the 

carpel chambers. 

COLOR CODE 

green: blade (a, c), petiole (b, d), stem (e), 

peduncle (g), pedicel (h), nectar 

glands (w) 

light green: stipules (f), bracts (i), sepals (j), petal 

veins (m), filament (p), pistil (o), 

carpels (s), styles (t), stigmas (v) 

light lavender: petals (l) 

red: sepal tips (k) 

yellow: stamens (n), anther (q) 

tan: ovary axis (u), styles (x), carpels (y), 

seed (z)

Carrot Family (Apiaceae) 

Members of this family form flowers in a dense, flattopped 

cluster (umbel, the reason for the old family 

name, Umbelliferae). Below the umbel, there is often a 

whorl of bracts. The number of sepals, petals and stamens 

of an individual flower in a cluster are each 5. 

The single pistil has an inferior ovary made up of 

2 carpels, an ovule in each. After fertilization, the ovary 

develops into a schizocarp fruit, which splits apart into 

2 mericarps that function as achenes (see 38). 

Also characteristic of plants in this family are the usually 

stem-sheathing leaf petioles. Compund leaf blades are 

usually several times divided into leaflets. Aromatic oils 

are present in leaves, stems, flowers, and fruits of these 

mostly biennial or perennial herbs. There are about 300 

genera and over 3,000 species. 

Of interest...food and flavoring: Anethum graveolens 

(dill), Angelica, Anthriscus cerefolium (chervil), Apium 

graveolens (celery), Carum carvi (caraway), Coriandrum 

sativum (coriander), Cuminum cyminium (cumin), 

Daucus carota cultivars (carrot), Foeniculum vulgare 

(fennel), Levisticum officinale (lovage), Myrrhis odorata 

(sweet cicely), Pastinaca sativa (parsnip), Petroselinum 

crispum (parsley), Pimpinella anisum (anise); 

ornamentals: Aegopodium podograria (goutweed, 

bishop’s weed), Ammi majus (lacy false bishop’s weed), 

Astrantia major (masterwort), Heracleum lanatum (cow 

parsnip), Trachymeme (blue lace-flower); poisonous: 

Cicuta maculata (water hemlock), Conium maculatum 

(hemlock), Heracleum mantegazzianum (giant hogweed). 

Cases of poisoning of humans and animals by 

plants are mainly caused by ingestion or skin contact. 

Some plants are poisonous only at certain stages of 

growth or certain times of the year. Cicuta maculata (water 

hemlock) grows mainly in wet areas and poisons cattle 

foraging in wet pastures in the spring. A small piece 

the size of a walnut is enough to kill a cow. Cicutoxin 

is concentrated in the roots, but is present in all parts 

of the plant. In humans if mistaken as roots of parsnips, 

Jerusalem artichokes or other roots, when eaten, the 

results are fatal. Conium maculatum (poison hemlock) 

was the plant that caused the death of Socrates. The 

plant, native to Eurasia, has become naturalized in the 

United States. It causes paralysis of the lungs. Heracleum 

mantegazzianum (giant hogweed) is not only an 

invasive plant but causes painful blisters on contact with 

human skin. This is called “contact dermatitis.” 

109 

Daucus carota Wild Carrot, Queen Anne’s Lace 

Wild carrot plants are biennial herbs, producing a basal 

rosette (a) of leaves and a tap root (b) the first year, 

with stem-borne leaves, flowers, and fruits the second 

year. The alternate, feathery-compound leaves (c) have 

petiole bases (d) that sheath the stem (e). This plant 

is not considered a “wild food,” as it greatly resembles 

other extremely poisonous plants in this family, which 

can be confused with it. Moreover, the fibrous white 

tap-roots are not edible like the orange, β-carotenecontaining 

tap roots of cultivated carrot. 

The umbel of flowers is supported by a peduncle (f) and 

has a whorl of compound bracts (g) below. The stems 

that branch out above the bracts are primary rays (h). 

Secondary rays or pedicels (i) support flowers in small 

clusters (umbellets, j) subtended by bractlets (k). This 

arrangement is termed a compound umbel. Outer 

flowers of the umbel have larger petals to attract pollinators, 

and the one center flower (l) has deep red petals. 

Lacking sepals, a carrot flower consists of 5 petals (m), 

which are occasionally pink instead of white, 5 stamens 

(n), and a single pistil. In the flower drawing, because 

of the pistil’s inferior (below other flower parts) ovary, 

only the 2 styles (o) on stylopodia (p) can be seen. The 

stylopodium is a nectar-secreting organ that attracts 

a variety of pollinating insects. Cross-pollination with 

other plants is not necessary, because the flowers are 

self-fertile. 

As the fruit develops, the parts of the pistil become more 

obvious. A stylopodium (p) with style (o) and stigma (q) 

is atop each carpel, the mericarp (r) of the schizocarp 

fruit. Hooked spines (s), which catch in animal fur, facilitate 

fruit dispersal. Fruit is also wind-dispersed. In autumn, 

the umbel of schizocarps (t) close inward to form 

a “bird’s-nest” in appearance. It closes in wet weather 

and opens when dry, further aiding fruit dispersal. 

COLOR CODE 

green: leaf (c), petiole (d), stem (e), 

peduncle (f), bracts (g), ray (h), 

pedicel (i) 

white: root (b), flowers (j), petals (m) 

red: center flower (l) 

yellow: stamens (n) 

light green: styles (o), stylopodium (p), stigma (q) 

tan: mericarp (r), spines (s), schizocarps (t)

Milkweed Family (Asclepiadaceae) 

The common characteristic in this family is an unusual 

flower (shown in the illustrated example). Otherwise, 

the appearance of these plants varies enormously. This 

family includes sturdy perennial herbs, shrubs, dainty 

vines, small trees, and succulent plants that resemble 

cacti. Usually, the stems have a milky, latex-containing 

sap. Simple leaves are in an opposite or whorled arrangement, 

but are sometimes alternate. There are 

about 250 genera and 2,000 species. Flowers occur 

singly or in various types of clusters. The fruit is a 

follicle that splits along one seam. 

Of interest...ornamentals: Araujia sericofera, Asclepias 

tuberosa (butterfly weed), A. curassavica (bloodflower), 

Ceropegia woodii (string-of-hearts), Cryptostegia 

grandiflora (purple allamanda), Hoya carnosa (wax 

plant), Huernia, Oxypetalum caeruleum (blue milkweed), 

Stapelia (carrion flower), Stephanotis floribunda 

(Madagascar jasmine); weed: Asclepias Cornuti (common 

milkweed, silkweed), Asclepias incarnata (swamp 

milkweed). Asclepias Cornuti (common milkweed) produces 

a milky acrid sap. Monarch butterfly larvae feed 

on the milkweed leaves which renders adults bad tasting 

to birds. This is advertised in their distinctive orange 

and black coloration. The somewhat smaller Viceroy 

butterfly mimics the coloration of the Monarch and 

avoids being attacked, even though as a willow-feeder, 

it is edible to birds. The common name silkweed refers 

to the use in former times of the silky seed as insulation 

in clothing and down in pillows. 

Cryptostegia grandiflora (India rubber vine, purple allamanda) 

from Madagascar was used to produce a commercial 

source of poor quality rubber latex. Now, this 

twining vine is used as an ornamental because of its 

beautiful flowers. Caution must be used when pruning, 

as the poisonous sap is very irritating to the skin. 

Matelea has sap once used as arrow poison. The old 

name Vincetoxicum is Greek for “subduing poison.” 

Asclepias tuberosa Butterfly-weed 

This perennial herb is an attractive, orange-flowered 

plant that does not have milky sap and can be cut for 

floral arrangements. The hairy stems (a) have alternate, 

lanceolate leaves (b) and terminate in flat-topped flower 

clusters (umbels). An umbel is a type of cluster in which 

110 

the peduncle (c) has many pedicels (d) arising at a common 

point, each supporting a flower (e). Individually, this 

specialized flower has 5 sepals (f) and 5 reflexed petals 

(g) that cover the sepals. Above the petals is a structure 

composed of a gynostegium (h) surrounded by 

a crown of 5 nectar horns. Each nectar horn consists 

of an upright hood (i) and a protruding crest (j). With 

nectar horns removed, the central portion of the gynostegium 

can be seen. In the area between the nectar 

horn attachments are 2 flaps (veils, k) with an opening 

between. A pin is shown inserted in this side opening. 

When the pin is raised through the slit opening, it dislodges 

another structure, a pair of pollinia, tucked into 

top-opening slits in the gynostegium. A pair of pollinia 

is a male part of the flower; there are five pairs. Each 

pair consists of 2 anther sacs (l) with arms (m), connecting 

them to a gland (n). 

The female part of the gynostegium cannot be seen 

from the outside. By opening two side flaps (k), the 

sticky stigmatic tissue (o) is exposed. There are 5 sets 

of flaps with stigmatic tissue between each, connecting 

internally to 2 styles (p). Below each style is a carpel 

(q), where numerous ovules (r) are attached in parietal 

placentation. So, all together, this flower has a 

single pistil composed of 2 ovaries (s) of a carpel each, 

2 styles, and enlarged 5-lobed stigma. 

How does a bee react to this flower? Bees are attracted 

to the nectar in the nectar horns. To position itself, the 

bee lands on the gynostegium. When a leg or an antenna 

slips between the side flaps, it is raised up (as 

the pin shown) and catches a pair of pollinia. Apparently, 

this does not bother the bee. With repeated slipping 

and sliding of many bees on many flowers, pollinia 

are removed from the top-opening slits and inserted in 

the side-opening flaps, achieving a high percentage of 

pollination. The fruits that result are follicles (t) of hairy 

seeds (u). 

COLOR CODE 

green: stem (a), leaf (b), peduncle (c), 

pedicel (d), sepal (f) 

orange: flower (e), petal (g), hood (i), crest (j) 

pale green: gynostegium (h, k), stigma (o), styles (p), 

carpel (q), ovary (s) 

yellow: anther sacs (l) 

tan: anther arms (m) 

brown: anther gland (n) 

white: ovules (r)

Nightshade Family (Solanaceae) 

There is no single characteristic common only to this 

family. A number of features are present. Flower petal 

lobes tend to overlap or have creases in a petal tube 

that in bud is folded fan-like. And, usually, the stamens 

are attached to the petals. Numerous ovules develop 

into numerous seeds in the berry or capsule fruit. 

The leaves are mostly alternate and simple, but size and 

shape vary greatly throughout the family. Usually the 

leaves are hairy and have a characteristic odor. Plant 

form ranges from herb to shrub to tree to vine. There 

are 90 genera and about 3,000 species. 

Of interest...ornamentals: Browallia, Datura arborea 

(angel’s trumpet), Nicotiana (tobacco, see 34), Nierembergia, 

Petunia, Physalis alkelengi (Chinese lantern), 

Schizanthus, Solandra (cup of gold); poisonous: 

Atropa Belladonna (deadly nightshade, belladonna, 

atropine), Datura stramonium (jimson weed), Nicotiana 

(tobacco, nicotine insecticide), Physalis heterophylla 

(ground cherry), Solanum Dulcamara (bitter 

nightshade), S. nigrum (black nightshade), S. pseudocapsicum 

(Jerusalem cherry); medicinal: Hyoscyamus 

niger (henbane, a source of alkloidal drugs), 

Atropa belladonna (source of alkaloids, atropine and 

hyoscyamine), Datura Stramonium (source of alkaloid 

drug hyoscyamine); food: Capsicum spp. (bell pepper, 

chilies, cayenne pepper, paprika), Lycoperiscon 

esculentum (tomato), Physalis ixocarpa (tomatillo, jamberry), 

P. peruviana (strawberry tomato, cape gooseberry, 

ground cherry), P. pruinosa (strawberry tomato), 

Solanum Melongena variety esculentum (eggplant, 

aubergine), S. tuberosum (potato, Irish potato). 

Potatoes are native to the central Andes of Peru. 

Indians collected wild potatoes before 6,000 B.C.E. 

There are eight species and as many as 5,000 varieties 

in many colors. Potatoes can grow almost anywhere except 

in high humidity areas. Potatoes are 99.9% fat-free 

and have a higher percentage of protein than soybeans. 

One potato supplies 1 /2 of the daily vitamin C requirement 

for an adult. As a crop, potatoes are worth billions 

of dollars. In the mid-1800s, due to the potato late blight 

(caused by the fungus Phytophthora infestans,see 46) 

millions of people died of famine in Ireland with the loss 

of potato crops. Half of the world’s crop is fed to livestock. 

It is also used to make vodka and aquavit, and 

can be used as starch, paste, and dye. As fuel for cars, 

one acre (0.40 hectares) of potatoes yields 1,200 gallons 

(4536 liters) of ethyl alcohol in a year. 

111 

Solanum dulcamara Bitter Nightshade 

Leaves on this wild, perennial vine are alternate and 

divided into 3 lobes (a). Flowers in the cymose cluster 

have jointed pedicels (c, d). (A cyme is a flat-topped 

cluster with the central flower opening first.) There are 

5 joined sepals (e) and 5 reflexed, purple petals (f) with 

green spots (g) at the base. The 5 stamens with short 

purple filaments (h) join anthers (i) around the pistil’s 

style (j). 

With the flower cut open, the stamens (h, i, k) surround 

the pistil’s superior ovary (l) and style (j, m), with 

the stigma (n) emerging at the top. Pollen is released 

from the stamens through pores (o) at the ends of the 

anthers. Nightshade fruits are small, red, poisonous 

berries (p). 

Lycopersicon esculentum Tomato 

Tomato flowers consist of joined sepals (q) with 6 lobes, 

joined petals (r) with 6 lobes, 6 stamens, and a single 

pistil. The stamens have short filaments and elongate, 

narrow-tipped anthers (s) that converge around the pistil’s 

style (t). Pollen is shed through longitudinal slits on 

the anthers’ inner surfaces. 

Physalis alkekengi Chinese Lantern 

A fruit that looks like a Chinese lantern is composed of 

an enlarged sepal tube (v), which encloses an orangered 

berry. 

Capsicum grossum Bell Pepper 

Pepper’s fruit type is a berry whose rind (w) changes 

from green to red at maturity. Seeds (x) develop on a 

central placenta (y). 

COLOR CODE 

green: leaf (a), petiole (b), pedicel (c, u), 

sepals (e, q), spots (g), style (j, t) 

purple: pedicel (d), petals (f), filament (h) 

yellow: anthers (i, s), stamens (k), petals (r) 

light green: ovary (l), style (m), stigma (n) 

red: berries (p), rind (w) 

orange: sepal tube (v) 

white: seeds (x), placenta (y)

Morning Glory Family 

(Convolvulaceae) 

Flowers in this family often have fused petals that are 

twisted when in bud and open in a funnel-shape or in a 

tube shape with a flat top. A pair of bracts usually subtends 

the usually bisexual flower. Sepals, petals, and 

stamens are each 5, with the stamens arising from the 

petals. There is a single pistil with a superior ovary composed 

of usually 2 carpels, which, when mature, form a 

loculicidal capsule. The plant tissues contain jointed 

latex-containing cells that produce a milky sap. 

Represented in this family are twining herbs, shrubs, 

and small trees. Heart-shaped, alternate, and simple 

leaves are most common. There are about 50 genera 

and about 1,800 species. 

Of interest...food: Ipomoea batatas (sweet potato); 

ornamentals: Calonyction aculeatum (moonflower), 

Convolvulus althaeoides, C. cneorum (silverbush), 

C. mauritanicus (ground morning glory), Dichondra 

(a ground cover), Ipomea purpurea (morning glory), 

I. tuberosa (wood rose), Porana paniculata (Christmas 

vine), Quamoclit pennata (cypress vine); weeds: Convolvulus 

spp. (bindweeds, which are drought-resistant 

due to their deep and extensive root systems.), Cuscuta 

(dodder, a parasitic plant with orange, thread-like stems 

that grow en masse in association with many different 

kinds of flowering plant hosts). 

112 

Convolvulus sepium Hedge Bindweed 

This plant is a perennial herb with a twining stem (a) and 

alternate, triangular leaves (b). Single flowers on long 

peduncles (c) arise in the leaf axils. At the base of the 

flower are 2 large bracts (d). Inside the bracts, 5 sepals 

(e) surround the funnelform tube of 5, pink, fused petals 

(f). The center of each petal lobe has a white stripe (g). 

With the petal tube cut open, the stamens’ petal attachment 

can be seen. Five filaments (h) arise from 

the petal tube and the anthers (i) meet and enclose the 

pistil’s stigma. Pollen is shed inwardly. 

With sepals, petals, and stamens removed, the parts of 

the pistil can be seen. There are 2 stigmas (j), a single 

style (k), and an ovary (l) composed of 2 fused carpels, 

forming one chamber. Within the chamber are 4 ovules 

(m). An orange disc (n), surrounding the base of the 

pistil, arises from the receptacle (o). 

Ipomoea batatas Sweet Potato 

Cultivated for its edible, underground, tuberous roots 

(p), the sweet potato plant is a tropical vine, but can be 

grown in southern temperate regions during summer 

months. 

COLOR CODE 

red-green: stem (a) 

green: leaf (b, q), peduncle (c), bracts (d) 

light green: sepals (e) 

white: stripe (g), filaments (h), anthers (i), 

stigma (j), style (k), ovary (l), ovules (m), 

receptacle (o) 

pink: petals (f) 

orange: disc (n), tuber (p)

Mint Family (Lamiaceae) 

Mint plants have square stems and mostly opposite 

leaves. Aromatic essential oils are usually present 

and account for the distinct and characteristic odors. 

Flowers have 5 fused petals that diverge into 2 lips 

(bilabiate). (The old family name, Labiatae, means 2lipped, 

where the corolla or calyx is divided into two differently 

shaped parts forming an upper and lower lip.) 

The single pistil has a superior, 4-lobed ovary, and a 

style that arises between the ovary lobes from the base 

of the flower (gynobasic style). The fruits produced 

are 4 nutlets. 

Usually, plants in this family are annual or perennial 

herbs, although shrubs, trees, and vines are also represented. 

There are about 200 genera and about 5,600 

species. 

Of interest...edible herbs: Majorana (marjoram), 

Mentha spp. (mints), Nepeta (catnip, catmint), Ocimum 

(basil), Origanum (oregano), Rosmarinus officinalis 

(rosemary), Salvia officinalis (sage), Satureja (savory), 

Thymus (thyme); ornamentals: Agastache barberi 

(giant hyssop), Ajuga (bugloss), Hyssopus (hyssop), 

Lamium (dead nettle), Lavandula (lavender), Nepeta 

(catmint), Perovskia (Russian sage), Phlomis alpina, 

Physostegia (false dragonhead, obedient plant), Salvia 

splendens (scarlet sage), S. viridis (painted sage), 

Scutelaria costaricaca, Solenostemon scutellanoides 

(coleus), Stachys macrantha (big betony), S. byzantina 

(lamb’s ears). 

113 

Salvia officinalis Sage 

This spring-flowering, perennial herb has square stems 

(a) with opposite, simple leaves (b). Two small flower 

clusters arise on opposite sides of the stem. Conspicuous 

ribs join the flower’s 5-lobed sepal tube (c). The 

5 fused petals (d) separate into an upper lip composed 

of 2 petal lobes and a lower lip consisting of 3 petal 

lobes. 

Cut open, the flower reveals several interesting features. 

Two stamens arise from the lower petal lip. For 

clarity, one stamen is shaded in the drawing. The filament 

(e) attaches to an enlarged connective (f) that 

allows for rotation of the anther sac (g), hence facilitating 

pollen dispersal by insects. 

As a visiting bee alights on the lower petal lip, pollen 

from the rotating anther sacs brushes the insect. After 

depletion of pollen, the stigmas (h) are lowered by 

the elongated style (i). Thus, pollen from other flowers 

is brushed on the stigmas by visiting bees, effecting 

cross-pollination. 

Nectar, the source of attraction to insects, is pooled below 

a ring of hairs (j) in the petal tube, secreted by a disc 

(k) at the base. The pistil’s gynobasic style (I) arises 

between the 4 lobes of the ovary (l). 

At fruiting time, when the persistent sepal tube is cut 

open, 4 nutlets (n) are revealed. 

COLOR CODE 

green: stem (a), pedicel (m) 

gray-green: leaves (b) 

purple-green: sepals (c) 

purple: petals (d), nectar disc (k), stigmas (h), 

style (i) 

white: filaments (e), connectives (f), hairs (j) 

tan: nutlets (n) 

yellow: anther sacs (g) 

light green: ovary (l)

Olive Family (Oleaceae) 

Characteristics in this family include flower parts in 2’s 

with the anthers of the stamens usually touching. The 

single pistil has a superior ovary of 2 fused carpels with, 

usually, 2 ovules in each carpel. 

Plants in this family are shrubs, trees, and vines with 

opposite leaves, which may be simple or compound. 

Some have evergreen, persistent leaves. Usually, the 

flowers are bisexual and have 4 sepals and 4 petals. 

Fruit types are berries, drupes, capsules and samaras. 

There are 29 genera with 600 species. 

Of interest...food: Olea europaea (olive); lumber: 

Fraxinus (ash); ornamentals: Abeliophyllum (white 

forsythia, Korean abelia-leaf), Chionanthus (fringe 

tree), Forsythia (golden bells), Jasminum (jasmine), 

Ligustrum (privet), Osmanthus (fragrant olive, tea olive, 

devil-weed), Syringa (lilac). 

In the countries surrounding the Mediterranean Sea, 

the olive tree, Olea europaea, has been in cultivation 

for over 4,000 years. The drupe fruit has a high oil 

content that is used both for oil production and preserved 

whole. Once trees are no longer productive, the 

wood is used to carve items such as bowls, jewelry, and 

roseries. 

In primitive naturalistic religions, it was believed that 

“spirits” inhabited certain trees. The olive tree had special 

significance as one of the most sacred. In summer, 

if a person slept under the tree, he of she would have 

pleasant dreams, as the evil spirits are afraid of the olive 

tree! 

Olive leaves were burned for protection from the “evil 

eye.” Accordingly, it was wise to have an olive tree 

planted near the dwelling place. On the Acropolis in 

Athens, Greece an olive tree is always growing near 

the Parthenon. Purportedly, the “evil eye” is the supposed 

power of some people to harm others by merely 

looking at them. 

Olive leaves, woven into crown wreaths, were used by 

the Greeks and Romans to reward winners in athletic 

games. 

An olive branch is traditionally a symbol of peace. On 

the seal of the United States, the American eagle faces 

toward an olive branch clutched in its right foot as 

opposed to the cluster of spears in its left foot. 

114 

Syringa vulgaris Common Lilac 

Persia (now Iran) is the original home of the common 

lilac. The leaves (c) of this shrub are opposite, simple, 

and have entire margins. Clusters of fragrant, tubular 

flowers (d) branch from a main flower axis (compound 

panicle). Flowers last only a few weeks but are 

a favorite for the scent and old-fashioned associations. 

There are many named cultivars. A loculicidal capsule 

(e) is the fruit type. 

Forsythia Golden Bells 

Originally from China, Forsythia was brought to 

Europe in 1844. Of the many species, special cultivars 

and hybrids have been developed. This shrub’s flowers 

emerge along the stem (f) in early spring. Although the 

shrub is hardy in the Northern Hemisphere, flower buds 

are frequently killed by late frosts. In its natural form, 

arching branches are covered with yellow flowers. 

The flower has 4 sepals (h) and 4 petals (i) joined at 

the base. Arising from the petal tube are 2 stamens 

(j) with back-to-back anthers. The pistil’s ovary (k) has 

many ovules (l) in axile placentation in each of the two 

carpels (m). There is a single style (n) and a 2-lobed 

stigma (o). 

Ligustrum vulgare Common Privet 

This plant is commonly used as a clipped hedge. If left 

to grow in its natural form, it produces fragrant flowers 

and can grow to 15 feet (5 meters) high. A drupe (r) is 

the fruit type of this shrub. 

Fraxinus pennsylvanica Green Ash 

The fruit on ash trees is a samara (t). The green ash 

tree is highly susceptible to the green ash tree borer 

insect pest; as a result, scores of green ash trees in 

Eastern United States are now dying or dead. 

COLOR CODE 

brown: stem (a, s), capsule (e) 

green: new shoots (b), leaves (c, g, q), 

sepals (h), pedicel (p) 

lilac: flowers (d) 

tan: stem (f), samara (t) 

yellow: petals (i), stamens (j) 

pale green: ovary (k), style (n), stigma (o) 

white: ovules (l) 

dark blue: drupes (r)

Figwort Family (Scrophulariaceae) 

Plants in this large family of 210 genera have characteristics 

found in many related families. They are 

mostly herbs or small shrubs that have various methods 

of obtaining nutrition, which include self-feeding 

(autotrophic), partial dependence on another plant 

(hemiparasitic), total dependence (holoparasitic), 

and dependence on dead or decaying organic matter 

(saprophytic). 

Usually, the leaves are alternate on round or square 

stems. Flower types vary greatly, but all are bisexual. 

Bracts below flowers are usually present. Flower sepals 

are usually joined and have 4-5 lobes. Joined petals 

form a tube that may have 2 lips (bilabiate) like a mint 

flower. Sometimes there are 5 stamens, but usually, 

there are 4 in 2 pairs of two different lengths (didynamous), 

with, usually, the fifth stamen reduced to a 

sterile structure or a scale. 

The single pistil has a superior ovary, or 2 carpels forming 

2 chambers, that usually matures into a capsule 

fruit. 

Of interest...ornamentals: Angelonia (angelonia), 

Alonsoa (mask flower), Antirrhinum (snapdragon), Calceolaria 

(slipper-flower), Cymbalaria (Kenilworth ivy), 

Diascia (twinspur), Mazus reptans, Mimulus (monkeyflower), 

Penstamon (beard-tongue), Russelia (coral 

plant), Satera (bacopa), Torenia (wishbone flower); 

wild: Castilleja coccinea (Indian paint-brush), Pedicularis 

(lousewort), Scrophularia (figwort), Verbascum 

(mullein), Veronica (speedwell), Veronicastrum 

(Culver’s-root); poisonous: Digitalis purpurea (foxglove). 

Leaves of this plant have several active and 

toxic glucosides: digitoxin, digitalin, digitonin. The 

poisons have a cumulative effect when ingested. Digitoxin 

was used in medicine to treat congestive heart 

failure and heart rhythm irregularities. It enhances and 

strengthens the force of the heart’s contractions. However, 

there are serious side effects; so usage is now out 

of favor in medical practice. 

Linaria vulgaris Butter-and-eggs, 

Common Toadflax 

Numerous, narrow leaves (a) arise on the stem (b) of 

this wild perennial. Peduncles (c) have bracts (d) below 

the pedicel (e). The flower’s sepal tube (f) has 5 lobes. 

115 

The bilabiate petals consist of an upper petal lip (g) 

with 2 lobes and a lower petal lip (h) with 3 lobes and a 

conspicuous elevated palate (a projection which closes 

the throat, i). Extending from the lower lip is a nectarcollecting 

spur (j). 

With the 2 petal lips cut apart, the 2 long (k) and 2 

short (l) stamens can be seen surrounding the pistil. The 

pistil has an ovary (m) consisting of 2 carpels containing 

numerous ovules (n) and a single style (o) and stigma 

(p). A nectar disc (q) surrounds the ovary base. 

A nectar-seeking bee separates the lips, slides its head 

between the rows of hairs on the palate (i), inadvertently 

transfers pollen to the stigma, sucks nectar from the 

spur, and is dusted with pollen from the anthers as it 

departs. 

Castilleja coccinea Indian Paint-brush 

As a saprophyte, annual plants are often found in a 

circle above buried organic material. The leaves (s) below 

flowers are 3-parted, bract-like and variable in form. 

Bright red bracts (u, v) surround the flower (t). This plant 

is commonly seen in meadows and ravines in mountainous 

regions. 

Verbascum thapsus Mullein 

Mullein is a biennial plant that forms a rosette of leaves 

the first year, and in the second year, a tall, stout stem 

(w) with alternate leaves (x), topped by a spike of yellow 

flowers (y, z). 

COLOR CODE 

green: leaves (a, s, x), stem (b, w), peduncle 

(c), bract (d), pedicel (e), sepals (f, z), 

disc (q) 

pale yellow: petal lips (g, h), spur (j) 

yellow-orange: palate (i) 

yellow: anthers (k), flowers (y) 

white: filament (l), style (o), ovules (n) 

red-purple: stem (r) 

pale green: ovary (m), stigma (p), flower (t), 

bract, shaded area (u) 

red: bract, unshaded area (v)

Gesneria Family (Gesneriaceae) 

This family is composed of mainly tropical plants. It includes 

herbs, shrubs, trees, vines, and epiphytes. In 

cool climates, the family is known for the ornamental 

houseplants such as African violets, cape primroses, 

and gloxinias. There are 125 genera with about 

2,000 species. 

The generally hairy leaves are usually opposite or occur 

in basal rosettes. Bisexual flowers arise in clusters 

or singly and have 5 sepals, 5 petals, 2 to usually 4 

stamens, and a single pistil. The ovary has 2 carpels 

fused into one chamber containing numerous ovules in 

parietal placentation. The position of the ovary may 

be superior, half-inferior, or interior. A nectar disc is under 

the ovary or nectar glands surround the ovary. A 

capsule is the usual fruit type. 

Aeschynanthus lobbianus Lipstick Plant, 

Blushwort 

Because of its trailing stems (a) with bright red flowers, 

this Indonesian plant can be attractively displayed 

in a hanging container. The fleshy leaves (b, c) are opposite 

and have smooth (entire) margins. Borne along 

the stem in leaf axils, the flower clusters have leaf-like 

bracts (d) at the base. Five hairy fused sepals (f) form 

a tube. 

116 

The flower developmental series shown reveals why 

Aeschynanthus is commonly called lipstick plant. As the 

flower develops, fused red petals (g) rise out of the sepal 

tube. The bilabiate (two-lipped) petals open into 2 upper 

and 3 lower lobes with darkly colored nectar guide 

markings (h), which attract bird pollinators. Protruding 

from the upper petal lobes are 4 anthers (i). 

Four stamen filaments (j) arise from the petals and join 

to form 2 pairs of anthers (i, k). Inside the petal tube, 

the pistil has an inferior ovary (l), a single stigma, and 

a style (m), which is surrounded at the base by nectar 

glands (n). 

Saintpaulia ionantha African Violet 

From Africa, but not a true violet (Viola, see 92), this 

plant forms a basal rosette of hairy leaves (o) with scalloped 

margins. Clusters of flowers range in color from 

white to pink to blue to purple, depending on the variety 

and hybrid cultivar. 

Basically, the flower consists of 5 sepals (q) and 5 petals 

(r), but extra petal-like structures (s), formed from stamens, 

may be present. The 2 functional stamens each 

have 2 anther sacs (t, v) and a wide filament (w). The 

pistil (x) has a superior ovary (y) covered with glandular 

hairs, and a style (z), which extends at an angle. 

COLOR CODE 

gray-green: stem (a), pedicel (e), leaves (o) 

green: leaf upper surface (b) 

light green: leaf underside (c), style (m), 

ovary (l, y), nectar glands (n), 

pistil (x, z) 

dark purple-red: bracts (d), sepal tube (f), 

petal markings (h), anthers (i, k) 

red: petals (g) 

white: filaments (j, w) 

brown: pedicel (p), sepals (q) 

purple: petals (r), staminodes (s), petal and 

staminode base (u) 

yellow: anthers (t, v)

Honeysuckle Family (Caprifoliaceae) 

Distinguishing features of this family include opposite, 

simple leaves without stipules. Flowers are usually 

bisexual and often in pairs. The stamens arise from 

the petals (epipetalous) and alternate with the petal 

lobes. 

The pistil’s ovary is inferior with 3–5 carpels. There is 

usually one ovule in each locule. The single style has 

stigmas equal in number to the carpels. Fruit types are 

berries or drupes and highly desired by birds. Plants in 

this family are mostly woody shrubs and vines. Many 

members make wonderful landscaping plants. There 

are about 18 genera and about 450 species. 

Of interest...ornamentals: Abelia × grandiflora (glossy 

abelia), Linnaea borealis (twinflower), Leycesteria, 

Lonicera × heckrottii (goldflame honeysuckle), Symphoricarpos 

(snowberry, coralberry), Viburnum acerifolium 

(mapleleaf viburnum), V. carlesii (Korean spice 

viburnum, and its fragrant hybrids: V. × burkwoodii, 

V. × carlcephalum, V. × juddii), V. cassinoides (witherod 

viburnum), V. dentatum (arrow-wood, so named for 

its straight stems formerly used by Native Americans 

for making arrows), V. lentago (nannyberry, sheepberry), 

V. nudum (possum haw viburnum), V. prunifolium 

(black haw), V. × rhytidophylloides (leatherleaf 

viburnum), V. opulus variety americanum (formerly 

V. trilobum, American cranberry bush; it has edible, 

astringent fruit, delicious when made into a jelly), V. 

rufidulum (rusty black haw), Weigela; wild: Sambucus 

117 

canadensis (elderberry, the fruit is used in jelly, pie, and 

wine making). 

Lonicera japonica Japanese Honeysuckle 

This honeysuckle is a woody, climbing vine. Once cultivated 

in the U.S., this species has become widely distributed, 

displacing native plants, and is now regarded 

as a noxious weed. 

The hairy stems (a) have opposite, simple leaves (b) 

with short petioles (c). A pair of bisexual flowers is borne 

on a short peduncle (d). At the base of each flower pair 

is a pair of leafy bracts (e). An individual flower has a 

tiny sepal cup (f) with even smaller bractlets (g) on each 

side. The petal tube (h) is divided into a four-lobed lip 

and a one-lobed lip. Five stamens (i) protrude from the 

long petal tube. 

The cut-open petal tube shows that the stamens arise 

from the top of the petal tube. The stamen’s filament 

(j) is attached to the center of the anther (k), providing 

for flexible movement. Extending from the nectar-filled 

petal tube is the pistil’s long, slender style (l) and stigma 

(m). Pollination is by moths, which are attracted to this 

highly scented, long-petal tube flower. 

A cross-section of the berry (n) fruit shows that the pistil’s 

inferior ovary is composed of 3 fused carpels (o). 

Paired berries develop from the paired flowers. 

COLOR CODE 

pale green: stem (a), style (l), stigma (m) 

green: leaves (b), petioles (c), 

peduncle (d), bracts (e), sepals 

(f), bractlets (g) 

pale yellow-orange: petals (h) 

white: stamens (i), filaments (j), 

anthers (k) 

black: berry (n)

Teasel Family (Dipsacaceae) 

There are only 11 general with 350 species in this small 

family of usually annual, biennial, or perennial herbs. 

The leaves are opposite. 

Bisexual flowers develop in a dense cone-shape head 

or on a spike. Individual flowers are surrounded at the 

base by a bract. Small sepals are joined into a cupshape 

or divided into 5–10 hairy or bristle-like segments. 

Petals are united into a tube with 4 or 2 stamens 

attached. The single pistil’s inferior ovary has one 

locule. The fertilized ovule develops into an achene fruit. 

Dipsacus sylvestris Teasel 

Teasel is a tall, biennial herb that grows in low, wet areas 

along roadsides and in old fields. Its ridged stems (a), 

covered with spines, have narrow, opposite leaves (b) 

without petioles (sessile). Below the compact flower 

head are long, upward-curved bracts (c). A narrow, 

pointed bract (d) at the base of each flower (e) lends 

a pincushion appearance to the flower head. 

An enlarged single flower shows its enclosing bract (d), 

the silky-haired sepal cup (f), and white petal tube (g), 

which divides into 4 purple, overlapping lobes (h). Four 

stamens (i), inserted in the petal tube, emerge free at 

the top. Pollen (j) is shed inwardly toward the stigma (k). 

With the petal tube and inferior ovary (l) cut open, the 

pistil’s style (m) and ovule (n) can be seen. The fertilized 

ovule develops into an achene (o) fruit. 

Of interest...ornamental: The dry cone-like heads (inflorescence) 

at maturity are collected for use in dried 

flower arrangements; utility: The dry cone-like heads 

with their bristle-like segments can be used to “card’ 

wool (like a comb) to remove extraneous matter from 

the wool. 

118 

COLOR CODE 

light green: stem (a) 

green: leaves (b), bracts (c), sepal cup (f) 

white: petal tube (g), pollen (j), stigma (k), 

ovary (l), style (m), ovule (n) 

lavender: bract (d), flowers (e), petal lobes (h), 

stamens (i) 

tan: achene (o)

Aster Family (Asteraceae) 

Asteraceae represents the largest dicot family, with 

about 25,000 species distributed worldwide. It includes 

herbs, shrubs, trees, epiphytes, vines, and succulents. 

Leaves show an extreme range of diversification, with 

an alternate, opposite, or whorled arrangement. The 

blades are simple to compound, lobed, needle-like, or 

scale-like. 

If a flower looks like a daisy, it is probably in the aster 

family. The common characteristic in this family is the 

head of many modified flowers (a composite of flowers). 

What appears to be a flower is actually a multiple 

false flower. There is an almost complete loss 

of sepals (calyx). Another characteristic includes having 

fused anthers forming a cylinder around the style 

(syngenesious condition). As the stigma and style 

grows up through the cylinder, it pushes the anthers 

out so as to facilitate pollen dispersal. This prevents 

self-fertilization. 

The flower’s single pistil has an inferior ovary composed 

of 2 carpels fused to form one chamber with one ovule 

that matures into an achene fruit without endosperm. 

Some of the flower modifications are shown with the 

two illustrated plants. 

Of interest...food: Artemisia dracunculus (tarragon), 

Carthamnus tinctorius (safflower), Chichorium endivia 

(endive), C. intybus (chicory), Cynara scolymus 

(artichoke), Guizotia abyssinica (niger seed), 

Helianthus tuberosus (Jerusalem artichoke), H. annuus 

(sunflower seeds, oil), Lactuca sativa (lettuce); 

medicinal: Artemisia annua (sweet wormwood, source 

of artemisinin, an anti-malaria drug); ornamentals: 

Ageratum, Aster, Calendula, Dahlia, Dendranthema 

(chrysanthemum), Echinops (globe thistle), Gaillardia, 

Gazania, Gerbera, Helianthus (sunflower), Helichrysum 

(strawflower), Leontopodium (edelweiss), Leucanthemum 

(daisy), Liatris (blazing star), Solidago 

(goldenrod, an attractive fall-flowering addition to the 

garden, height varies with the cultivar and flowers attract 

many beneficial insects, commonly assumed that this 

insect-pollinated plant is the culprit that causes hayfever 

when the blame goes to wind-pollinated plants such 

as Ambrosia, ragweed), Stokesia, Tagetes (marigold), 

Zinnia; insecticide: Tanacetum coccineum (pyrethrum, 

painted daisy); weeds: Ambrosia (ragweed), Cirsium 

(thistle), Sonchus (sow-thistle), Taraxacum (dandelion), 

Xanthium spinosum (cocklebur), a seedhead with tiny 

hooklike spines on the surface clings to animal fur to 

119 

facilitate seed dispersal. George de Mestral invented 

a fastener combining the hooks like those of the cocklebur 

seed head and loops like the fabric of his burred 

pants. He called it “Velcro,” combining the words velour 

and crochet; poisonous pasture plants: Eupatorium 

rugosum (white snakeroot), Helenium (sneezeweed), 

Senecio (ragwort). 

Rudbeckia hirta Black-Eyed Susan, Coneflower 

This plant is a biennial or short-lived perennial herb. The 

habit drawing shows its leaves (a) of variable shape and 

with some having petioles (b). Long peduncles (c) support 

flower heads composed of yellow, sterile, ray flowers 

(d) which surround a cone of brown-petaled, fertile 

disc flowers (e). Hairy bracts (f) below the flower head 

can be seen in the vertical section drawing. Many small 

disc flowers (e) are borne on a conical receptacle (g). 

Evolutionary modifications of Asteraceae flowers include 

sepals that are reduced to bracts (h) and petals 

(i) that are fused to form a tube of 5 lobes. Stamen 

modifications include filaments (j), of the 5 stamens, attached 

inside the petal tube and lance-shaped anthers 

(k) joined to form a cylinder. After pollen is shed, the 

stigma (l) rises through the cylinder. This prevents selffertilization. 

Below the double stigmas are the pistil’s 

style (m) and inferior ovary (n) with 1 ovule (o). 

Tagetes patula Marigold 

A marigold flower head is supported by a peduncle (p) 

and has fused bracts (q) below the head. Outer ray 

flowers (r) are, mainly, unisexually female, while inner 

disc flowers (s) are bisexual. Both have bracts (t) and 

both have a pistil with a double stigma (u) and an ovary 

(v) below other flower parts. The bisexual disc flower, 

cut open, shows the pistil’s ovule (w) attached to the 

base of the ovary and the style (x) that rises through the 

cylinder of the stamens’ anthers (y) after pollen is shed. 

COLOR CODE 

green: leaves (a, b), peduncle (c, p), bracts (f, q) 

yellow: ray petals (d), anthers (k, y) 

brown: disc petals (e, i), bract (h) 

white: receptacle (g), filaments (j), ovule (o,w) 

light green: stigmas (l, u), style (m, x), ovary (n, v), 

orange: ray petals (r), disc petals (s) 

tan: bracts (t)

Water-plantain Family (Alismataceae) 

This primitive monocot family is composed of aquatic 

plants that are annual or perennial herbs. Parts of the 

bisexual or unisexual flower are arranged in whorls of 3 

sepals, 3 petals, and 3 to numerous stamens and pistils. 

A pistil’s ovary contains usually one ovule in basal 

placentation. The fruit is an achene. There are 14 genera 

and about 100 species. 

The basally sheathing leaves are either floating or have 

long petioles that rise above water level. Leaf blades are 

variable, linear to round, or the bases are arrowheadshaped 

(saggitate), or arrowhead-shaped with narrow, 

basal lobes nearly at right angles (hastate condition). 

Of interest...depending on the point of view, these 

plants are waterweed pests and can be very common 

weeds in rice (Oryza sativa) paddies or useful for 

ornamental pool gardens: Alisma plantago-aquatica 

(water plantain), Echinodorus (bur-head), Sagittaria 

(arrowhead); wildlife food: most genera. 

Saggittaria latifolia Wapato, Arrowhead 

Fibrous roots (a) anchor this perennial herb in the mud 

substrate of aquatic habitats. Older plants have swollen 

tubers at the ends of rhizomes (underground stems). 

The common name, wapato, was used by Native Americans 

for the edible tubers. The leaf’s sheathing petioles 

(b) vary in length with the water depth. Arrowheadshaped 

leaf blades (c) are narrow, as shown, to wide. 

The peduncle (d) of the raceme bears whorls of unisexual, 

male flowers (e) at the top and female flowers 

(f) below. Having male and female flowers on the same 

individual plant is termed a monoecious condition. 

An enlargement of the male flower shows more clearly 

the bract (g) at the pedicel (h) base. Both male and 

female flowers each have 3 persistent, green sepals (i) 

and 3 white petals (j), which are shed early. 

The male flower has 24 to 40 stamens (k) in whorls. 

Pollen is shed through slits on the anther sacs (l). 

Seen in a vertical section, the female flower has numerous, 

densely aggregated pistils (n) borne on the receptacle 

(o). Each pistil has a simple stigma (p), a short 

style (q), and one basal ovule (r) in the ovary (s). The 

fruits produced are numerous, flat achenes. 

120 

COLOR CODE 

white: roots (a), petals (j), filament (m), 

receptacle (o), ovule (r) 

red-green: petioles (b) 

green: blades (c), peduncle (d), bract (g), 

pedicels (h), sepals (i), pistils (n), 

stigma (p), style (q), ovary (s) 

yellow: stamens (k), anther (l)

Spiderwort Family (Commelinaceae) 

These popular houseplants are annual or perennial 

herbs derived from tropical and subtropical regions. 

Closed sheathing leaf petioles and flower parts in 3’s 

are common characteristics. There are 38 genera and 

about 600 species. 

The alternate succulent leaves have entire margins and 

parallel venation. Leaf-like bracts sometimes partially 

enclose the flower clusters. The bisexual flower can 

also occur singly. Parts of the flower include 3 sepals, 

3 petals, 6 stamens (or 3 stamens and 3 staminodes 

or one functional stamen), and a single pistil. The stamens’ 

filaments often have hairs. The pistil has a superior 

ovary of 3 fused carpels, one style, and one stigma. 

There are no nectar glands. A loculicidal capsule is 

usually the fruit type. 

Of interest...ornamentals: Callisia (striped inch 

plant),Commelina(dayflower),Cyanotis,Dichorisandra, 

Gibasis (Tahitian bridal veil), Rhoeo discolor (Mosesin-the-bulrushes), 

Tinantia, Trandescantia spp. (spiderwort, 

wandering Jew, inch plant), Zebrina pendula 

(wandering Jew); biology: The staminal hairs of 

Tradescantia (spiderwort) are commonly used in introductory 

plant biology labs to observe cytoplasmic 

streaming (cyclosis) under the microscope. 

121 

Gibasis geniculata Tahitian Bridal Veil 

The thin, trailing stems (a), small leaves (v, c, d), and 

tiny flower clusters (e) provide a delicate appearance 

to this plant. It is often displayed in hanging containers. 

Because of the sheathing leaf petioles (b), the 

stem has a jointed appearance. The wavy-margined, 

alternate leaves are green above (c) and purple (d) 

below (due to the presence of anthocyanin reddishpurple 

pigment). 

Branching from the peduncle (f), pedicels (g) support 

the flowers. The flower has three sepals (h), 3 petals 

(e), 6 stamens (i), and a single pistil (j). The stamen 

has tufts of hairs (k) on the filament (l) below the anther 

(m). The pistil consists of stigma (n), style (o), and a 3lobed, 

superior ovary (p). Fleshy sepals (h) remain and 

enclose the capsule fruit. 

Zebrina pendula Wandering Jew 

This low, spreading succulent (fleshy) herb has purple 

(q) and silvery-green (r) striped leaf blades with 

hairy petioles (s) that sheath the stem (t). Zebrina 

is from the Latin for zebra, and refers to the striped 

leaves. 

COLOR CODE 

green: stem (a, t), upper blade surface 

(c), peduncle (f), stripes (r), 

petioles (s) 

purple: petiole (b), lower blade surface 

(d), pedicel (g), margin and 

center stripes (q), bract (u, v) 

white: petals (e), hairs (k), filament (l) 

light green: sepals (h), pistil (j), ovary (p) 

yellow: stamens (i), anther (m) 

dark pink-lavender: stigma (n), style (o), petals (w)

Sedge Family (Cyperaceae) 

Distinguished from grasses, which have hollow, round 

stems, sedges have solid-pithed, often 3-sided stems. 

Grasses have leaves arranged in two ranks, whereas 

sedge leaves usually emerge from a stem node in three 

directions (three-ranked). As in grasses, each sedge 

leaf is organized into a blade (lamina) and an enclosing 

sheath. One bract or scale subtends each flower. There 

are 100 genera and about 4,000 species. 

Sedges are usually bog or marsh plants and grow in 

clumps or extend from creeping, underground, rhizomelike 

stems. Minute flowers are arranged in spikelets. 

Sepals and petals are reduced to bristles, hairs, or 

scales, or are absent. Usually there are 3 stamens and 

a single pistil with a superior ovary consisting of 2 to 3 

carpels fused to form one chamber with one ovule. The 

pistil’s style sometimes forms a beak on the achenetype 

fruit. 

Of interest...ancient usage: Cyperus papyrus (pith 

used to make paper), Cyperus spp. (mat grass, hay 

grass, roof thatching), Eleocharis spp. (basket making), 

Scirpus spp. (bulrushes for basketwork, mats, 

chair seats); food: Eleocharis tuberosa (Chinese water 

chestnut tubers); water garden plants: Cyperus 

alternifolius (umbrella plant), Carex spp., Leiophylum 

spp., Scirpus spp.; cattle fodder: Carex spp. (sedges); 

wildlife food: most genera. 

122 

Cyperus strigosus Umbrella Sedge 

This perennial sedge has a smooth, three-sided stem 

(a), leaves (b) at the base, and clusters of flower 

spike (c) subtended by leaf-like bracts (d). A ray (e) of 

spikes has loosely arranged, linear spikelets (f). Older 

plants have a short, knotty rhizome-like underground 

stem. 

A spikelet consists of a double row of overlapping, 

bisexual flowers, each enclosed by a flattened scale 

(g, h). In the flower enlargement (shown), 3 stamens 

have been shed. Remaining are a green-keeled (g), flattened 

scale with golden, translucent sides (h) and the 

pistil. The pistil consists of a 3-parted style (i) and an 

ovary (j). The fruit that develops is a 3-angled, beakless 

achene (k). 

Carex hystericina Porcupine Sedge 

Unisexual flowers are formed on separate spikelets 

of this sedge. Both male (l) and female (m) spikelets 

have leaf-like bracts (n) below. The female pistil (o) 

is composed of a 3-branched style (p) and an ovary 

surrounded by a flask-shaped sac, the perigynium (q), 

with a 2-toothed beak (r). A small scale (s) subtends 

the pistil. As in other sedges, an achene (t) fruit is 

formed. 

COLOR CODE 

green: stem (a), leaves (b), bracts (d, n), 

rays (e), scale keel (g) 

gold-green: spikelets (f) 

gold: scale side (h) covering ovary (j) 

tan: style (i), achene (k, t), male spikelet (l) 

light green: female spikelet of pistils (m, o), 

perigynium (q, r), scale (s) 

brown: styles (p)

Grass Family (Poaceae) 

The grass flower is unlike any other plant family’s flowers. 

Within a spike (a), the flower unit is called a 

spikelet. An exaggerated separation of the structures 

is shown in the spikelet diagram. For reference, the diagram 

and the spikelet drawing of Secale cereale (rye) 

have the same letter for a described structure. 

The primary axis of the spikelet is called the rachilla 

(b). At the base of the spikelet are two bracts called 

first glume (c) and second glume (d). The next bracts 

are called lemmas (e) and may have a bristlelike appendage 

(awn, f). A soft inner bract is called the palea 

(g). The remaining parts comprise a floret (h). Each 

spikelet may have one or more florets, which are unisexual 

or bisexual. 

There are no sepals or petals. Instead, there are 2 or 3 

lodicles (i). Lodicles enlarge with turgor pressure and 

cause the lemmas and palea to expand, exposing the 

stamens and/or stigmas at pollination time. 

Grasses are wind-pollinated. There are usually 3 stamens 

with freely moving (versatile) anthers (j) and a 

single pistil with 2, usually feathery, stigmas (k). The 

pistil’s ovary (l) is superior and contains one ovule. The 

fruit is usually a grain (caryopsis, m) or a berry in some 

bamboos. 

Grasses are annual or perennial herbs except for bamboo, 

which is woody at maturity. Roots (n) are fibrous 

and adventitious roots arise from stem nodes. The 

stems, called culms (o) are usually hollow and round 

with one leaf (p) to a node (q). Leaves are alternate in 

two rows (ranks = a so-called distichous arrangement) 

up the culm. The leaf consists of a blade (lamina, r) 

and a sheath (s), which encircles the culm (stem), and 

has parallel venation (t). Where the leaf blade diverges 

from the culm is often an appendage, the ligule (u), and 

sometimes, as in rice (Oryza sativa) two sickle-shaped 

auricles that clasp the sheath. 

Economically, Poaceae is the most important plant 

family. Of interest...food crops: Avena sativa (oats), 

Hordeum (barley), Oryza sativa (rice), Saccharum officinarum 

(sugarcane), Secale cereale (rye), Setaria 

italica (millet), Sorghum bicolor (sorghum), Triticum 

(wheat), Zea mays (corn); shelter: Bambusa (bamboo); 

fodder: Agrostis (bentgrass), Dactylis glomerata 

(orchard grass), Phleum (timothy), Setaria italica (foxtail 

grass), Sorghum, Zea; lawn turf: Agrostis (bent 

123 

grass), Cynodon dactylon (Bermuda grass), Festuca 

spp. (fescue grass), Poa (bluegrass), Stenotaphrum 

(St. Augustine grass), Zoysia (zoysia grass); industry: 

various grasses (insulation materials, newsprint, ethyl 

alcohol); decontamination: Molasses is made from refined 

sugar derived from sugarcane (Saccharum officinarum). 

Besides its culinary use, molasses spurs the 

growth of one type of bacteria that creates favorable 

growth conditions for other bacteria that digest contaminants 

in polluted groundwater. 

Parts of a Grain 

The Triticum (wheat) grain diagram shows the source of 

vitamins, nutrients, and metabolites that we utilize (see 

also 40, corn grain). Wheat bran, composed of pericarp 

(v), seed coat (w) and protein–rich aleurone layer 

(x), contains vitamin B complex (thiamine, riboflavin, 

niacin, pyridoxine, pantothenic acid), cellulose, phosphorus, 

calcium, and iron. Endosperm (y) is processed 

into flour that contains mostly starch and some protein. 

Wheat germ refers to the embryo (z) and is a source of 

vitamin B complex, vitamin E, vitamin A, protein, iron, 

fat, sodium, copper, zinc, magnesium, and phosphorus. 

Wild wheat was domesticated by humans about 10,000 

years ago. There are now about 22,000 cultivars. There 

are two main categories: hard wheat to make bread 

and soft wheat to make pasta, pastry, crackers, cakes, 

cookies and cereal. 

Rice (Oryza sativa) is sold as either white or brown 

rice. White rice is “polished” with consequent removal of 

the protein-rich aleurone layer outside the endosperm. 

Brown rice has the aleurone layer left intact and is nutritionally 

far better than starch-rich white rice. 

COLOR CODE 

yellow: spikes (a), glumes (c, d), anthers (j), 

pericarp (v) 

green: lemmas (e), leaves (p), leaf blade (r), 

leaf sheath (s), ligule (u) 

light green: palea (g), lodicle (i), stigmas (k), 

ovary (l), culm (o) 

tan: grain (m), roots (n), seed coat (w) 

orange: aleurone layer (x) 

white: endosperm (y), embryo (z)

Arrowroot Family (Marantaceae) 

Arrowroot plants are tropical, perennial herbs with underground 

stems (rhizomes). Because of the flower 

structure, this family is considered to be the most advanced 

in its order, the Zingiberales. Other families 

included in the order are the bird-of-paradise family 

(Strelitziaceae), the banana family (Musaceae), the 

ginger family (Zingiberaceae), and the canna family 

(Cannaceae). 

In the arrowroot family, there are 30 genera and 350 

species. The flower is bisexual but the fertile male part 

has been reduced to one stamen, which consists of one 

anther sac. One to 5 sterile stamens (staminodes) are 

also present. 

The single pistil has an inferior ovary with 3 chambers, 

although by evolutionary reduction, only one ovule may 

be produced. The fruit is a loculicial capsule or berrylike, 

and the seeds often have a fleshy covering (aril). 

The arrow root leaf is composed of a petiole with a 

sheath covering and a joint where the blade is attached. 

The joint is a pad-like swelling (pulvinus) that controls 

“sleep movements.” Within the pulvinus, the vascular 

tissue is grouped in the center, surrounded by sensor 

and flexor parenchyma cells, which can expand and 

contract. Leaves are alternate and 2-ranked, emerging 

in one plane on opposite sides of the stem. Venation is 

pinnate from the midrib and parallel. 

Of Interest...food: Maranta arundinacea (West Indian 

arrowroot) cultivated for the starchy rhizome: ornamentals: 

Calathea mackoyana (peacock plant), Calanthea 

zebrina (zebra plant), Calathea ornata, Maranta leuconeura 

kerchoveana (prayer plant, red-spotted arrowroot, 

rabbit tracks), Thalia dealbata (water canna). 

Maranta leuconeura massangeana Prayer Plant 

The common name, prayer plant, is derived from the 

orientation of the leaves at dusk. During daylight the 

124 

leaves are in a horizontal position. As light fades at sunset, 

the leaves take a vertical position that appear like 

hands in prayer. 

This small herbaceous plant is cultivated primarily as a 

foliage-type houseplant for its brightly colored leaves. 

The stem (a) has a sheath (b) at nodes and the leaf 

petiole has a winged sheath (c). Where the petiole joins 

the blade is a short, jointed segment, a pulvinus (d), 

where blade movement occurs in response to light and 

dark (nyctinastic response). 

The blade coloring is unusual, consisting of red parallel 

lines (e) that follow the pinnate venation pattern, a band 

(f) of yellow-green on both sides of the midrib area, with 

the remaining blade area (g) a dark green. The lower 

blade surface (h) is purple-red. In bud (i), the leaves are 

rolled. 

Tiny flower bud (j) clusters (panicles) havepedicels 

(k) enclosed by bracts (l) at the base. Each flower 

has 3 sepals (n), a fused petal tube consisting of 3 

lobes (o) and 3 petal-like staminodes (p). A fourth 

staminode (r), fused to the petal tube, extends from the 

colored staminodes. It has one fertile anther sac (s) attached 

to the side of a hood (r) that encloses the pistil’s 

stigma (t). 

With physical disturbance of the hooded staminode covering, 

the stigma (t) springs free as the style (u) coils 

down to its fusion point (v) on the staminode. At the 

same time, the few large pollen grains are propelled 

from the anther sac. The pistil’s inferior ovary (s) is below 

the sepals. 

COLOR CODE 

green: petiole sheath (c), petiole pulvinus (d), 

peduncle (m) 

purple-green: stem sheath (b), bracts (l) 

red: vein lines (e) 

yellow-green: midrib band (f) 

dark green: stem (a), remaining blade area (g) 

purple: lower blade surface (h), leaf bud (i), 

shaded area of staminodes (q) 

lavender: flower buds (j), staminodes (p) 

light green: pedicel (k), sepals (n), ovary (w) 

white: petals (o), staminode hood (r), 

anther sac (s), stigma (t), style (u)

Palm Family (Arecaceae) 

Palms are second to the grasses (see 123) in economic 

importance. In the tropics, they may be a source of food, 

clothing, shelter, and fuel. The palms, numbering about 

3,500 species, mostly consist of trees. Shrubs and vines 

are also represented. 

Lodoicea maldivica has the world’s largest seed, a 

“double coconut,” made up of a two-lobed drupe. 

Raphia fainifera has the largest flowering plant leaf, up 

to twenty meters long. 

Palms have a single apical bud, called “heart of palm.” 

When it dies or is removed, the plant dies. Tree-like 

forms have an unbranched trunk with a terminal crown 

of leaves, commonly called “fronds,” which emerge one 

at a time from the apical bud. Lignin, deposited in cell 

walls of stem (trunk) tissues provides sturdiness. As 

monocotyledons, palms have no vascular tissue in the 

stem; so there is no secondary growth (see monocot 

stem, 15). 

The leafy frond is made up a blade, a petiole, and 

a sheathing base. Blade types are: fan-shaped with 

feather-like (pinnate) veins, as in Lodoicea (a); fanshaped 

with veins arising from one point (palmate), as 

in Sabal (b); feather-shaped (pinnately compound), 

as in Chamaedorea (c); or feather-shaped, twicedivided 

(bipinnately compound) asinCaryota (see 

126). 

Regardless of shape, the young leaf (e) looks like a rod 

with a length-wise strip that peels down like a zipper, to 

free the one to many leaflets that unfold like a fan. The 

leaf petiole may be smooth or toothed on its margin. 

Small flowers are usually formed in loose clusters, 

called panicles (f), which have one or more bracts at 

125 

the base. Commonly, the plants have separate male 

and female flowers (unisexual) on the same plant 

(monoecious), or on separate plants (dioecious), 

while others have flowers with both male and female 

parts within one flower (bisexual). Flower parts are usually 

in 3’s, being separate or fused. Flowers are wind-, 

insect- or self-pollinated. 

Usually the fruit has one seed and is a berry or drupe 

type. The outside wall of the fruit can be fleshy, fibrous or 

leathery. Storage tissue (endospem) within the seed is 

oily or fatty rather than starchy. In coconuts (Cocos nucifer), 

it is liquid encased within the solid coconut “meat” 

that makes up the solid part of the endosperm. 

Of interest...economic plants: Areca catechu (betel 

nut palm), Calamus and Caemonorops (rattan 

cane), Cocos nucifera (coconut palm), Copernicia (carnauba 

wax), Elaeis guineesis (oil palm), Metroxylon 

(sago palm), Phoenix dactylifera (date palm), Paphia 

pendunculata (raffia, used as twine to tie tall 

plants to supports); ornamentals: Arecastrum (queen 

palm), Arenga pinnata (sugar palm), Caryota mitis 

(fishtail palm), Chamaedorea elegans (parlor palm), 

Chamaerops (European fan palm), Chrysalidocarpus 

(Madagascar feather palm), Cocothrinax argentea 

(silver palm), Erythea spp. (Mexican fan palms), 

Howeia spp. (curly palm, sentry palm, flat palm), 

Jubaea spectabilis (coquitos palm), Livistona spp. (fan 

palms), Metroxylon (sago palm), Rhapidophyllum (needle 

palm), Rhapis (lady palm), Roystonea regia (royal 

palm), Sabal palmetto (cabbage palmetto), Serenoa 

(saw-palmetto), Trachycarpus fortunei (Chinese windmill 

palm), Thrinax (peaberry palm), Washingtonia filifera 

(sentinel palm); food: heart-of-palm; building materials: 

large palm leaves are used as “thatch” on roofs 

of houses/huts in the tropics. 

COLOR CODE 

yellow-green: leaf (a) 

green: leaf (b) 

dark green: leaf (c), stem (d), new leaf (e) 

orange: panicle (f)

Palm Family (continued) 

Sabal palmetto Cabbage Palmetto 

This palm is native to the coastal regions of southeast 

United States, the West Indies, and Venezuela. It may 

grow up to 21 meters high. The leaf (see 125) is fanshaped 

with palmate venation. Long stems of many 

panicles arise with the leaves. A single panicle (a) with 

small, white bisexual flowers (b) is shown. The flower 

is without a stem (sessile) and consists of 3 bracts (c) 

at the base, 3 fused sepals (d), 3 petals (e), 6 stamens 

(f), and a single pistil (g) with a superior ovary having 3 

fused carpels. 

Chamaedora elegans Parlor Palm, Collina, 

Neathe Bella 

The parlor palm, native to South America, is often used 

as a potted houseplant. The fronds (leaves, see 125) 

are feather-shaped. Arising with the leaves at the crown 

are branched racemes (panicles, h) of flowers which 

develop into black drupes (i). Bracts (j) enclose the 

base of the panicle. 

Chamaedora ernesti variety augusti 

Instead of a single trunk, like the parlor palm (see 125) 

this Mexican species has many leafy stems arising from 

a common base. The panicle (k) has many bracts (l) 

enclosing the base and only a few stalks of flowers (m). 

Caryota mitis Fishtail Palm 

Twice divided (bipinnately compound) leaves distinguish 

this palm. The sub-leaflets (n) are fishtail-like. 

Leaves emerge along the stem instead of in a crown at 

the top. Panicles of flowers also arise along the length 

of the trunk. Flowers mature into fruits (o, p) starting 

from the end of the stalk (q). The drupes drop off as 

they mature. 

126 

COLOR CODE 

white: flowers (b), petals (e), pistil (g) 

green: panicle stalk (a), sub-leaflets (n), 

immature drupe (o) 

tan: bracts (c, j, l), stalk end, shaded (q) 

light green: sepals (d), stalk, upper portion (r) 

orange: panicle stalks (h) 

black: drupe (i), mature drupe (p) 

dark green: panicle stalk (k) 

yellow: stamens (f), flowers (m)

Arum Family (Araceae) 

A unique characteristic of this family is the elaborate 

reproductive structure consisting of a fleshy spike of 

flowers, the spadix, subtended by a leaf-like bract, the 

spathe. These mostly tropical and subtropical plants 

are usually terrestrial herbs growing on the forest floor. 

Because of their low-light tolerance, they are popular 

as houseplants in cool climates. Poisonous calcium oxalate 

crystals are present in plant tissues and there may 

be a milky sap (latex). 

The leaves are simple or compound, occur at the 

base or are alternate on the stem, and have petiole 

bases that sheath the stem. The small flowers on the 

spadix are bisexual or unisexual. The flowers have 

an odor of rotten flesh, which attracts fly pollinators 

(see 34). There are 1 to 6 stamens and a single pistil 

with one to many carpels. Sepals and petals that 

look alike (tepals) may be present. The fruit type is a 

berry. There are about 110 genera and about 2,000 

species. 

Of interest...ornamentals: Aglaonema (Chinese evergreen), 

Amorphophallus (voodoo lily), Anthurium 

(flamingo flower), Caladium (elephant’s-ear), Dieffenbachia 

(dumb-cane), Helicodicerus, Monstera deliciosa 

(Swiss-cheese plant, cut-leaf philodendron), Philodendron, 

Pistia (water lettuce), Scindapsis (pothos, 

devil’s-ivy), Spathiphyllum (flame plant), Zantedeschia 

aethiopica (calla lily); food: Alocasia (taro), Colocasia 

(taro), Xanthosoma (tannia); native wild plants: 

Arisaema triphyllum (Jack-in-the-pulpit), Calla palustris 

(wild calla), Orontium (golden club), Peltandra (arrow 

arum), Symplocarpus foetidus (skunk cabbage, 

see 34). 

As skunk cabbage shoots develop in early spring 

in northern temperate regions, they melt the snow 

around each shoot. This heat is generated through high 

127 

respiration rates in the developing spadix, in sufficient 

amounts to melt the snow and ice. 

Spathiphyllum Flame Plant 

This perennial herb has simple leaf blades (a) with 

sheathing petioles (b). The spadix (c) of bisexual flowers 

is subtended by a white petal-like spathe (d). Each 

flower (e) has 6 tepals (f) enclosing 6 stamens. The anther 

(g) of the stamen is shed form a fleshy filament 

(h) after pollen is released. The pistil (i) has a flattened 

3-part stigma (j) with ovules (k) in basal placentation 

(see 28). 

Arisaema triphyllum Jack-in-the-pulpit 

This North American wild flower is a perennial herb that 

arises from a solid bulb-like structure (corm, see 12). 

The compound leaf blade (l) is divided into 3 leaflets 

(hence, triphyllum). The petiole (m) is enclosed by a 

sheath (n) at the base. Plants with one compound leaf 

have male flowers on the spadix, while plants with two 

compound leaves have female flowers. 

This unusual plant has unisexual flowers on the same 

plant at different times. Young plants with one compound 

leaf have only male flowers at the base of the 

spadix. In subsequent years, two leaves develop from 

the corm, and in a developmental sex change, the 

spadix produces only female flowers. Energy is expended 

in the production of fruit; so food produced in 

the leaves and translocated to the corm must be sufficient 

to assure that shoot and reproductive (flowering 

and fruiting) development occurs the following year. 

In autumn, on plants with female flowers, a cluster of 

red berries (s) is revealed as the spathe and leaves (t) 

wither. 

COLOR CODE 

green: blades (a), petioles (b, m), leaflets (l), 

sheath (n) 

white: spadix (c), spathe (d), tepals (f), pistil (i), 

stigma (j), ovules (k), filaments (h) 

yellow: anthers (g) 

light green: outer spathe (o), spadix (q), peduncle (r) 

purple: inner spathe (p) 

red: berries (s) 

tan: peduncle (u), leaves (t)

Lily Family (Liliaceae) 

Lily flowers have 3 sepals and 3 petals that look alike 

(tepals), 6 stamens, and a single pistil with a superior 

ovary composed of 3 fused carpels. Fruit types are 

septicidal or loculicidal capsules or berries. 

This large family of about 250 genera and about 4,600 

species consists mostly of perennial herbs with narrow, 

parallel-veined leaves and underground storage organs 

such as rhizomes, bulbs, corms, or tubers. Some plants 

are evergreen succulents, as in Aloe and Haworthia or 

vines as in Smilax (see 16). 

Leaf characteristics vary greatly from basal and linear 

with parallel veins to cauline (growing on a stem), as 

shown in the illustration. Some have net (reticulate)venation 

(Trillium). Others have leaf-tip tendrils (Gloriosa). 

Asparagus leaves are scale-like. 

Of interest...food: Allium spp. (onion, shallot, leek, 

garlic, chives), Asparagus officinalis (asparagus); 

medicine: Aloe vera (sap from leaves is used to treat 

burns and relieve the pain of sunburn), Colchicum 

(colchicine), Urginea (red squill); ornamentals: Allium, 

Aloe, Asphodeline (Jacob’s rod), Agapanthus 

(lily-of-the-Nile), Calochortus, Colchicum autumnale 

(autumn crocus), Convallaria majalis (lily-of-the-valley), 

Eremurus (foxtail lily), Fritillaria, Gloriosa (gloriosa lily), 

Haworthia, Hemerocallis (daylily), Hosta (hosta), 

Hyacinthus (hyacinth), Kniphofia (torch lily, red-hotpoker), 

Lilium spp. (lilies), Muscari (grape-hyacinth), 

Sansevieria (snake plant, bowstring-hemp, leopard 

lily), Scilla (squill), Smilax (greenbriar, see 16), Tulipa 

(tulip); native wild plants: Erythronium spp. (dogtooth 

violet, trout lily), Maianthemum (false lily-of the 

valley), Lilium, Medeola virginiana (Indian cucumberroot), 

Polygonatum (Solomon’s seal), Smilacina spp. 

(false Solomon’s seal), Trillium spp., Uvularia (bellwort), 

128 

Veltheimia viridifolia); poisonous: Amianthemum 

(stagger-grass), Convallaria majalis (lily-of-the-valley), 

Ornithogalum umbellatum (star-of-Bethlehem), Veratrum 

(false hellebore), Zigadenus Nuttallii (death 

camas, poison camas, merryhearts). 

Lily is a confusing common name. Examples of a few 

plants that are called lilies include lilies (Lilium), and 

daylilies (Hemerocallis) in the lily family (Liliaceae). 

Then, there are waterlilies (Nymphaea) in the waterlily 

family (Nymphaeae, 79), peace lily (Spathiphyllum) 

in the arum Family (Araceae, 127), blackberry lily 

(Belamcanda chinensis) in the iris family (Iridaceae, 

129), and spider lilies (Lycoris spp.) in the amaryllis 

family (Amaryllidaceae). 

Lilium michiganense Michigan Lily 

This wild lily is a perennial herb that grows to two meters 

in height. It is native to the midwestern prairie region 

of the United States. Whorls of leaves (a) occur 

along the stem (b). At the top are flowers with 6 orange 

or, rarely, orange-red, recurved tepals (c) that arise on 

peduncles (d). 

The flower also has 6 stamens (e) with each filament 

(f) attached in the center of the anther (g), providing 

for free movement. The single pistil (h) has a superior 

ovary composed of 3 carpels (i) with numerous ovules 

(j) in axile placentation, a long style (k), and a 3-lobed 

stigma (l). Sweat bees, butterflies and hummingbirds 

are the pollinators. 

A loculicidal capsule (m) is formed from the ovary. 

One of the 3 locules shows a stack of flat, winged 

seeds (n). 

COLOR CODE 

green: leaves (a), stem (b), peduncle (d), 

pistil (h) 

orange: tepals (c), anther (g) 

brown: stamens (e), capsule (m) 

light green: filament (f), style (k), stigma (l) 

white: carpels (i), ovules (j) 

tan: seed (n)

Iris Family (Iridaceae) 

Plants are perennial herbs or subshrubs with underground 

storage organs of rhizomes, bulbs, or corms. 

The leaves sheath at the base, overlapping each 

other transversely to form a flat fan-like arrangement 

(equitant) unique to this family. Venation is parallel. 

The 3 sepals of flowers in this family are colored and 

petal-like. They may differ in size, shape, and color from 

the 3 petals. The bisexual flower has 3 stamens and a 

single pistil with an inferior ovary composed of 3 fused 

carpels. The fruit type is a loculicidal capsule. There 

are about 70 genera and about 1800 species. 

Of interest...ornamentals: Antholyza, Belamcanda 

chinensis (blackberry or Chinese lily), Crocus, Eustylis, 

Freesia, Gladiolus, Iris, Ixia, Moraea, Nemastylis, Neomarica, 

Sisyrinchium, Tigridia; commercial: Crocus 

sativus (saffron flavoring, saffron dye), Iris rhizomes 

(orris root). 

Iris germanica Flag, Bearded Iris, German Iris 

Iris plants are perennial herbs with a rhizome (a) storage 

organ and adventitious roots (b). Sword-shape leaves 

(c) overlap at the base in a fan-like arrangement. 

Flower color is wide-ranging in cultivated hybrids. It 

varies from white, yellow, orange, blue, purple, red, pink, 

to tan and various bicolors. A pair of green bracts (d) 

occurs below the elaborate flower. Bracts cover a flower 

bud (e). The 3 petal-like sepals (f), “falls,” are bearded 

129 

with hairs (g). The 3 upright petals (h), “banners,” curve 

inward. Above each sepal is a stamen (j). 

In the flower structure drawing, an upright stamen made 

up of filament (k) and anther (l) can be discerned clearly. 

Nectar glands (m) occur where the filament emerges 

from the sepal tube (f). 

Where is the pistil? The bulge below the sepal tube is an 

obviously inferior ovary (n) with indentations denoting 

the three fused carpels. In an ovary cross-section, each 

carpel (o) has a chamber (locule, p) with ovules (q) in 

axile placentation. 

In the flower structure drawing, only one portion remains 

unidentified. What looks like a petal with crested 

wings above is one of 3 styles (r) with a flap of tissue, 

the stigma (s). 

Pollination involves insects. When a bee (t, u) alights on 

the sepal, it is guided by the beard hairs and color markings 

to the nectar location. As it works its way through 

a tunnel between style (v, r) and sepal (f) to the nectar 

glands, pollen on its body from another flower is rubbed 

off onto the stigma flap (w, s). Then, as the bee backs 

out of the flower, its hairs are dusted with pollen that is 

shed outwardly from anther sacs ( j, l). At maturity, the 

sepals raise upward against the styles, closing off the 

tunnels. 

The iris fruit is a loculicidal capsule (x) with seeds. 

COLOR CODE 

tan: rhizome (a), roots (b), capsule (x) 

green: leaves (c), bracts (d), bud (e), 

peduncle (i) 

yellow: beard (g), bee’s thorax (t) and 

abdomen (u) 

optional: 1 color from text: sepals (f), petals (h), 

styles (r, v) 

white: stamen ( j), filament (k), anther (l), nectar 

glands (m), ovary (n), carpel (o), ovules 

(q), stigma (s, w)

Orchid Family (Orchidaceae) 

The orchid flower is so specialized that the illustrated 

species is needed for a description of its structures. In 

general, the flower is usually bisexual, has 3 sepals that 

may resemble the 3 petals in color and form, a column of 

fused stamens and stigmas, and an inferior ovary composed 

of 3 carpels. Flower colors and color patterns 

vary widely. Nectar, odor, and form of the flower attract 

pollinators (specific in many cases). The fruit is a capsule 

that contains very tiny seeds. Since the endosperm 

aborts as seeds mature, a mutualistic fungal relationship 

has evolved that provides a source of metabolites 

for seed germination. 

The plants are generally leafy, sometimes leafless. 

Leaves are alternate, very rarely opposite, whorled or 

reduced to scales. They are simple, thickened, usually 

linear, strap-shaped or round, and basally sheathing the 

stem. These perennial herbs are distributed worldwide 

and comprise the largest plant family, with an estimated 

30,000 species. They are terrestrial and saprophytic, 

deriving nutrients from soil and dead organic matter. 

Or they are epiphytic, attached to the surface of another 

plant, where they obtain nutrients from the atmosphere 

and debris accumulations among the roots. Orchids 

have fungus-root (mycorrhizal) association. 

Nutrient storage organs may be swollen stems (pseudobulbs, 

see 16) or swollen root-stem tubers, which 

the Greeks called “orchis” for their testiculate appearance; 

hence, the orchid name. Roots of most epiphytes 

are covered with a layer of white-colored dead corky 

cells called velamen. Habitats vary enormously from 

dry sand to acidic bogs and wet meadows, from temperate 

forest and mangrove swamps to tropical cloud 

forests. There is even an underground orchid, Thizanthella 

gardneri. 

Of interest...flavoring: Vanilla (vanilla extract from 

capsules, commonly called beans); wild: most wild orchids 

are considered to be endangered species and 

are legally protected. In the United States, there are 

about 62 native genera; ornamentals: Anagrecum, 

Brassavola nodosa (lady-of-the-night, named for release 

of scent at night when moth pollinators will 

be attracted), Brassia spp. (spider orchids), Cattleya, 

Cymbidium, Dendrobium, Epidendrum, Habenaria spp. 

(fringed orchids), Laelia, Miltonia spp. (pansy orchids), 

Odontoglossum, Oncidium, Paphiopedilum spp. (lady’s 

slipper orchids), Phalaenopsis spp. (moth orchids), 

Stanhopea, and Vanda are a few examples. In the 

130 

quest for more exotic specimens, growers combine 

genera through plant breeding to form multigeneric 

types. For example Sophrolaeliocattleya is a hybrid 

composed of Sophronitis, Laelia,and Cattleya, abbreviated 

as Slc. Further tinkering has produced Slc. Jewel 

Box ‘Scheherazade,’ with Sophronitis coccinea, used 

to produce red hybrids; Laelia is used to produce 

free flowering and a fleshy substance, and Cattleya is 

used to produce size and modify form of foliage and 

flower. 

Cattleya bowringiana 

This plant is a tropical perennial epiphyte. Pseudobulbs 

(a) provide nutrient storage. Reduced leaves (b) 

cover the stem. Expanded leaves (c) are alternate and 

strap-shaped. A sheath (d) encloses the base of the 

peduncle (e). In this genus, the flower’s sepals (f) are 

strap-shaped, whereas, the 3 petals (g) are ruffled. 

In orchids, the central petal, called a lip, is usually 

larger and highly modified, sometimes occurring in quite 

bizarre forms. The lip encloses the column, resulting 

from a fusion of male and female parts. At the 

tip of the column is an anther cap (h) with 4 masses 

of pollen, called pollinia (i), tucked into 2 pocket-like 

structures. A pollinium has a sticky pollen sac (j) and 

a hooked caudicle (k). The remaining end of the column 

is formed by 3 fused fertile stigmas (l) with the end 

of the terminal stigma forming a sterile, sticky flap, the 

rostellum (m). 

An insect follows the nectar guides (n) in order to locate 

the nectar tube (o), dislodges the anther cap, and 

carries pollinia to another flower, where they stick to 

the rostellum. The 3-carpelled ovary (p), surrounding 

the nectar tube, contains minute ovules. The remaining 

part of the column (q) is stamen-style tissue, and is 

therefore, bisexual. A capsule (r) fruit is formed. 

COLOR CODE 

tan: pseudobulb (a), reduced leaves (b), 

withered petals (s) 

green: expanded leaves (c), sheath (d), 

peduncle (e), capsule (r) 

pink-purple: sepals (f), petals (g) 

yellow: pollinia (i), pollen sac (j) 

white: anther cap (h), caudicle (k), stigmas (l), 

rostellum (m), nectar tube (o), ovary (p), 

column (q) 

purple: nectar guides (n)

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Bloomfield Hills, MI: Cranbrook Institute of Science, 

1972. 

Wagner, Jr., Warren H, “Fern,” Encyclopaedia Britannica, 

237–248, 1974. 

Wagner, Jr., Warren H. “Systematic Implication of the 

Psilotaceae,” Brittonia 29(1):54–63, January–March 

1977. 

Weatherbee, Ellen Elliott and James Garnett Bruce. Edible 

Wild Plants of the Great Lakes Region. P.O. Box 8253, Ann 

Arbor, MI: 1979. 

Whittaker, R.H. and Lynn Margulis. “Protist Classification and 

The Kingdoms of Organisms,” Bio Systems, Vol. 10:3–18, 

Elsevier/North Holland: Scientific Publishers Ltd., 1978. 

Wigglesworth, V. B. The Life of Insects. New York: Mentor 

Book, New American Library (Times Mirror), 1964. 

Wilson, Adrian. The Design of Books. Salt Lake City: 

Peregrine Smith, 1974. 

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1997. 

132

Glossary of Word Roots 

a not, without (acephala) gamet spouse, sex cell (gamete) 

ab away from (abscise) gamo union, marriage (oogamy) 

aleuron flour (aleurone) gen origin, birth (gene) 

andro male (androecium) genus race (genus) 

angio box, vessel (angiosperm geo earth (epigeous) 

sporangium) glab bald (glabrous) 

anth flower (perianth) gland secrectory spot (glandular) 

antheros flowery (antheridium) glut glue (glutinous) 

anti against (antipodal) gymn naked (gymnosperm) 

apertur opening, hole (triaperturate) gyn female (gynoecium) 

api tip, apex (apical) habitus condition, physique (habit) 

arche beginning (archegonium) hal salt (halophyte) 

asco sac (ascocarp) hemi half (hemiparasite) 

ate provided with, (perfoliate) hetero other, different (heterospory) 

formed into hex six (hexagonal) 

auto self (autotrophic) holo entire (holoparasitic) 

basidio small base (basidiocarp) homo same, alike (homospory) 

bi two, double (biloba) hydro water (hydroponics) 

cap head (capitate) hyph web (hyphae) 

capill hair (capillitium) hypo below (hypogeous) 

carp fruit (schizocarp) idium diminutive ending (antheridium) 

caul stem (cauline) il diminutive ending (lentil) 

cephal head (acephala) infra below (infrared) 

chloro green (chlorophyll) inter between (intercalary) 

chrom color (chromosome) intra within (intracellular) 

cid cut, kill (septicidal) iso equal, homogenous (isogamy) 

circ circle (circinate) karyron nut, nucleus (eukaryote) 

cleisto closed (cleistothecium, lab lip (bilabiate) 

cleistogamous) lamel plate, layer (lamella) 

coll glue (collenchyma) lamin blade (Laminaria) 

coma hair (comose) lance lance, blade (lanceolate) 

cyan dark blue (anthocyanin) leuco white (leucocyte) 

cyst bladder, bag (pneumatocyst) lig strap, ribbon (ligulate) 

cyt cell (leucocyte) lith stone (Lithops) 

dendr tree (dendrite) loc a small place, cell (locule) 

dent tooth (dentate) ligne wood (lignin) 

derm skin (epidermis) logos discourse, study (ecology) 

di two, separate (dicot) macro large, long (macroscopic) 

dictyo net (Dictydium, mega large (megaspore) 

dictyosome) meiosis reduction (meiosis) 

dichotomos cut into two (dichotomous) meri part, segment, (mericarp, 

el diminutive ending (pedicel) component meristem) 

endo inside (endocarp) meso middle (mesophyll) 

epi upon (epiphyte) micro small, tiny (microphyll) 

equinus horse (Equisetum, mitos thread (mitosis) 

equitant) mono one, single (monocot) 

erythr red (phycoerythrin) morph form, structure (dimorphic) 

eu true, good (eukaryote) myco fungus, mushroom (Basidiomycota) 

ex from, beyond (excise) myx slime (Myxomycota) 

exo outside (exocarp) nat born, borne (circinate) 

fer bearer (conifer) nom name (binomial) 

fil thread-like (filiform) ode like (phyllode) 

fissio splitting (fission) oec household (dioecious, ecology) 

flagellum whip (flagellum) oid like (rhizoid) 

flav yellow (riboflavin) ol little (petiole) 

flor flower (inflorescence) orth straight (orthotropism) 

fol leaf (perfoliate) ostiol little door (ostiole) 

fungus mushroom (fungus) ov egg (ovule, ovary) 

funiculus a small cord (funiculus) paleo ancient (paleobotany) 

133

palm hand (palmate) septum partition, wall, (septate) 

palustr swamp (palustris) enclosure 

para beside (parasite) sessilis fit for sitting (sessile) 

pect comb (pectinate) soma body (somatic) 

ped, pod foot, stalk (stylopodium, soros heap (sorus) 

peduncle) species kind (species) 

pelt shield (peltate) sperm seed (angiosperm) 

per through, by means of (perfoliate) sphen wedge (sphenophyll) 

peri around (perianth) sporo seed, spore (sporophyte) 

phellos cork (phelloderm) stell star (stellate) 

phil love (Philodendron) strobilos twisted object, top, (strobilus) 

phloos bark (phloem) pinecone 

phore bearer (antheridophore) stoma mouth (stomate) 

phyle tribe (phylogenic) stroma cushion, mattress (stroma) 

phyll leaf (sporophyll) stylo pillar (stylopodium) 

phyco seaweed (phycoerythrin) sub under, less than (subtropical) 

phyte plant (epiphyte, super, supar above, over (superior) 

phytoplankton) syn, sym together, with, at the (synergid) 

pinn feather (pinnate) same time 

plast thing molded (protoplast) taxis arrangement, order (taxonomy) 

ploid fold (polyploid) terra earth (terrestrial) 

plume feather (plumose, plumule) tetra four (tetraspore) 

pneum lung, air, gas (pneumatocyst) thall shoot (thallus) 

poly many, much (Polyporus) tri three (triaperturate) 

por small opening (pore, poricidal) trichom hair (trichome) 

prim first (primordial) trop bend (tropism) 

pro before (prophase) troph nourish, food (autotrophic) 

protiston the very first (Protista) tuber knob, swelling (tuberous) 

proto first, original (protoplast) ul little (pinnule) 

pseud false (pseudobulb) uni one (unisexual) 

psilos bare, mere (Psilotum) vor eat (insectivorous) 

pterid fern (Pteridophyta) xanthos yellow (xanthophyll) 

pyle gate (micropyle) xer dry (xerophyte) 

rad root (radicle) xylon wood (xylem) 

reticulum a small net (reticulate) zygo yoke, pair (zygote, zygospore) 

rhap needle (Rhapidophyllum) 

rhiz root (mycorrhizae) 

rhodon rose color (Rhodophyta, Singular (Plural) Endings 

Rhododendron) 

ros rose (rosette) alga (algae) 

sagitt arrow (sagittate) mitochondrion (mitochondria) 

sapro rotten (saprophyte) nucleus (nuclei) 

schiz deeply divided (schizocarp) phytum (phyta) 

scis cut (abscise) 

sect cut (dissect) 

semi half (Semibegoniella) 

Metric Equivalents 

nanometer (nm) = 10 −9 meter 

1 micrometer (micron, µm) = 10 −6 meter 

1 millimeter (mm) = 0.001 meter, 0.04 inch 

1 centimeter (cm), 10 mm = 0.01 meter, 0.39 inch 

2.54 centimeters = 1 inch 

1 decimeter, 10 cm = 3.9 inches 

0.91 meter = 1 yard 

1 meter (m), 100 cm = 3.28 feet 

134

Index 

Aaron’s-beard, 98 

Abies, 73 

Abrus precatorius, 100 

Absidia, 47 

Abutilon, 90 

Acacia, 23, 100 

Acalypha hispida, 103 

Acer 

ginnala, 105 

japonicum, 105 

macrophyllum, 105 

negundo, 35 

palmatum, 105 

platanoides, 105 

pseudoplatanus, 105 

saccharinum, 14, 38, 105 

saccharum, 26, 105 

Aceraceae (Maple Family), 35, 105 

Acetabularia, 58 

Achimenes, 116 

Achlya, 46 

Aconitum, 80 

Adder’s-tongue ferns, 67 

Adiantum, 67, 72 

Aegopodium, 109 

Aeschynanthus lobbianus, 116 

African violet, 116 

Agar, 20, 57 

Agaricus, 50 

Aglaonema, 127 

Agrostemma githago, 87 

Agrostis, 123 

Ajuga, 113 

Albizzia, 100 

Albugo, 46 

Alder, 35, 84 

Aleurites fordii, 103 

Alfalfa, 12, 100 

Algae (see also Plant Kingdom) 

Blue-green “Algae,” 4, 6, 24, 41, 44, 

54,70 

Brown Algae, 4, 41, 59, 60, 61 

Golden Algae, 41, 56 

Green Algae, 4, 41, 54, 58, 62 

Red Algae, 4, 41, 57 

Yellow-green Algae, 41, 56 

Alisma, 120 

Alismataceae, 120 

Alismatidae, 75 

Allium (onion), 16, 49, 128 

Allomyces, 46 

Almond, 99 

Alnus, (alder), 35, 84 

Alocasia, 127 

Aloe, 128 

Althea rosea, 90 

Altingis, 81 

Alyssum, 75, 96 

Amanita, 50 

Ambrosia, 119 

American chestnut, 48, 83 

American elm, 38, 82 

Amianthemum, 128 

Amorphophallus, 127 

Amur maple, 105 

Anabaena, 44, 70 

Anacardiaceae, 106 

Anacardium occidentale, 106 

Anagrecum, 130 

Andreaea, 63 

Andromeda glaucophylla, 97 

Anemone, 80 

Anemonella, 80 

Anethum graveolens, 26, 109 

Angelica, 109 

Angel’s trumpet, 111 

Angiosperms, 75 

Anise, 109 

Anthoceros, 63 

Anthriscus cerefolium, 109 

Anthurium, 75, 127 

Antigonon, 89 

Antirrhinum, 115 

Aphanomyces, 46 

Apiaceae, 109 

Apical dominance, 19 

Apium graveolens, 109 

Apple, 4, 16, 31, 39, 49, 75, 99 

Apricot, 99 

Aquilegia, 81 

Arabis, 96 

Araceae (Arum Family), 23, 34, 127 

Arachis, 100 

Araucaria, 73 

Arborvitae, 73 

Arbutus, 97 

Arctostaphylos uva-ursi, 97 

Arcyria, 45 

Areca catechu, 125 

Arecaceae, 125, 126 

Arecastrum, 125 

Arecidae, 75 

Arenaria, 87 

Arenga pinnata, 125 

Aril, 73, 102 

Arisaema triphyllum, 127 

Armillaria, 50 

Armoracia, 96 

Arrow arum, 127 

Arrowhead, 120 

Arrowroot, 124 

Arrowroot Family, 124 

Arrow-wood, 117 

Artemisia dracunculus, 119 

Artichoke, 119 

Artist’s fungus, 50 

Arum Family, 23, 34, 127 

Asclepiadaceae, 110 

Asclepias 

curassavica, 110 

syriaca, 38, 110 

tuberosa, 110 

Ash, 35, 99, 114 

Asparagus officinalis, 128 

Aspen, 50, 95 

Aspirgillus, 48 

Asplenium nidus, 67 

Aster, 19, 119 

Asteraceae, 119 

Aster Family, 119 

Asteridae, 75 

Asterionella, 56 

Astilbe, 98 

Astraeus, 53 

Astragalus, 100 

ATP (adenosine triphosphate), 24 

Atropa belladonna, 112 

Aubrieta, 96 

Aucuba, 101 

Auricularia, 49 

Aurinia saxatilis, 96 

Australian gum tree, 75 

Autotroph, 55, 58, 115 

Auxin, 19, 20 

Avena sativa (oat), 19, 20, 26, 49, 123 

Avocado, 78 

Azalea, 97 

Azolla, 44, 67, 70 

Baby’s-breath, 87 

Bacillariophyceae, 56 

Bacillus radicicola, 43 

Bacteria, 6, 12, 24, 25, 41, 42, 45 

Bald cypress, 73 

Balsam poplar, 95 

Bamboo, 123 

Bambusa, 123 

Banana Family, 124 

Banana shrub, 77 

Barberry, 23, 49 

Bark, 9, 10, 15 

Barley, 26, 49, 123 

Basil, 113 

Basket-of-gold, 96 

Bauhinia, 100 

Bay laurel, 78 

Bazzania, 63 

Bean, 12, 14, 40, 100 

Bearberry, 97 

Beauty-bush, 117 

Beebalm, 113 

Beech, 35, 52, 83 

Beech Family, 35, 83 

Beet, 2, 4, 12, 88 

Begonia, 12, 93 

Begoniaceae, 93 

Begonia Family, 93 

Begoniella, 93 

Beilschmiedia, 78 

Belamcanda, 129 

Bell morel, 48 

Bell pepper, 111 

Bells-of-Ireland, 113 

Bellwort, 128 

Berberis (barberry), 23, 49 

Bergamot, 113 

Bermuda grass, 123 

Beta (beet), 2, 4, 12, 88 

Betel nut palm, 125 

Betula 

papyrifera, 84 

pendula, 75, 84 

Betulaceae (Birch Family), 35, 84 

Biennial, 12, 26, 87, 109, 115, 118, 119 

Big leaf maple, 105 

135

Bindweed, 112 

Birch, 35, 52, 75, 85 

Birch Family, 35, 85 

Bird-of-paradise Family, 124 

Bird’s-nest fern, 67 

Bird’s-nest fungus, 53 

Bishop’s-cap, 98 

Bitter nightshade, 111 

Bittersweet, 102 

Blackberry, 99 

Blackberry lily, 129 

Black-eyed Susan, 119 

Black locust, 38 

Black medic, 38 

Black nightshade, 111 

Black oak, 39 

Black raspberry, 39, 99 

Bladderwort, 23 

Blood-flower, 110 

Blueberry, 97 

Bluegrass, 123 

Blue-green “Algae,” 4, 6, 24, 41, 44, 54, 

70 

Blue lace-flower, 109 

Blue milkweed, 110 

Blushwort, 116 

Bog rosemary, 97 

Boston fern, 67 

Boston ivy, 104 

Botrychium, 67 

Bougainvillea, 23 

Bouncing Bet, 87 

Bowstring-hemp, 20, 128 

Box elder, 35 

Bracken fern, 67 

Bract, 23, 29, 33, 34, 36, 38, 75, 77, 83, 

87, 93, 95, 101, 103, 109, 112, 

117, 118, 119, 122, 123, 124, 126, 

127, 129 

Brasenia, 79 

Brassavola, 130 

Brassia, 130 

Brassica, 38, 96 

Brassicaceae (Mustard Family), 38, 96 

Bridal wreath, 99 

British soldiers, 54 

Broccoli, 96 

Browallia, 111 

Brown Algae, 4, 41, 59, 60, 61 

Brussels sprouts, 96 

Bryophyte, 63 

Bucklandia, 81 

Buckwheat, 89 

Buckwheat Family, 89 

Bud 

axillary (lateral) bud, 14, 19 

flower bud, 29 

terminal bud, 14, 19, 25 

Bud scale, 14, 35, 82, 83 

Bud scale scar, 14 

Bugbane, 80 

Bugloss, 113 

Bulb, 8, 12, 16, 18, 128, 129 

Bull-bay, 77 

Bulrush, 122 

Bunchlberry, 101 

Bur-head, 120 

Burning bush, 102 

136 

Butter-and-eggs, 115 

Buttercup, 80 

Buttercup Family, 80 

Butterfly-weed, 110 

Butterwort, 10, 23 

Cabbage, 97 

Cabbage palmetto, 125, 126 

Cabomba, 79 

Cactaceae, 4, 16, 85, 86 

Cactus Family, 4, 16, 85, 86 

Cafta, 102 

Caladium, 127 

Calamites, 43, 66 

Calamus, 125 

Calathea, 124 

Calceolaria, 115 

Calcium carbonate, 2, 63 

Calcium oxalate, 127 

California laurel, 78 

Calla lily, 127 

Calla palustris, 127 

Callirhoë, 90 

Callisia, 121 

Calodendrum, 107 

Calonyction aculeatum, 112 

Caltha, 80 

Calvatia, 53 

Caemonorops, 125 

Camphor, 78 

Camptosorus, 67 

Candy-tuft, 96 

Cannaceae,123 

Canna Family, 124 

Cantaloupe, 94 

Cape chestnut, 107 

Cape primrose, 116 

Capillitium, 45, 53 

Caprifoliaceae, 117 

Capsella bursa-pastoris, 96 

Capsicum, 111 

Caraway, 109 

Carbon dioxide, 24, 25, 43, 47 

Carbon fixation, 3, 24 

Carex hystericina, 122 

Carnation, 87 

Carnauba palm, 125 

Carnegiea gigantea, 36 

Carnivorous plants, 19, 23, 91 

Carrion-flower, 110 

Carrot, 4, 12, 38, 109 

Carrot Family, 109 

Carophyllaceae, 87 

Carum carvi, 109 

Caryophyllidae, 4, 75 

Caryota mitis, 125, 126 

Cashew, 106 

Cashew Family, 106 

Casparian strip, 13 

Cassia, 100 

Castanea, 83 

Castilleja coccinea, 115 

Castor-bean, 103 

Catha, 102 

Catnip, 113 

Cattail Family, 35 

Cattleya, 130 

Cauliflower, 96 

Cayenne pepper, 111 

Cedar, 49, 73 

Celastraceae, 102 

Celery, 109 

Cell structure 

cell organelles, 2, 3, 7, 18, 41, 59 

amyloplast, 3, 13 

chloroplast, 2, 3, 10, 13, 22, 24, 55, 

56, 58, 59 

chromoplast, 2, 3 

dictyosome, 2, 3 

endoplasmic reticulum, 2, 3 

leucoplast, 2, 3 

mitochondrion, 2, 3 

nucleus, 2, 3, 5, 6, 7, 10, 30, 31, 32, 

37, 41, 44, 45, 58 

plastid, 2, 3, 41 

ribosome, 2, 3, 43 

vacuole, 2, 4, 5, 59 

cell wall, 2, 3, 5, 7, 8, 11, 13, 43, 44 

chromosome, see Chromosome 

cytoplasm, 2, 3, 5, 7, 8, 18, 24, 43, 58 

middle lamella, 2 

nucleoid, 6, 43 

nucleolus, 2, 7, 58 

plasma membrane, 2, 5,43 

pit field, 2, 8, 10, 11, 72 

protoplast, 2, 8, 43, 56 

Cell types 

antipodal cell, 32 

bulliform cell, 22 

collenchyma cell, 8 

companion cell, 8, 11 

cork cell, 9, 10, 15, 22 

egg cell, 27, 30, 32, 46, 56, 59, 60, 61, 

62, 63, 64, 66, 67, 71 

epidermal cell, 10, 13, 22 

eukaryotic cell, 2, 41, 42 

fiber cell, 8, 11, 22 

guard cell, 10, 22, 24 

laticifer, 11 

mother cell, 30, 31, 32 

parenchyma cell, 8, 11, 13, 22, 60, 124 

prokaryotic cell, 41, 43, 44 

sclereid (stone cell), 8, 11, 22 

sclerenchyma cell, 8, 22 

sex cell (gamete), 6, 30, 45, 46, 55, 57, 

59, 60, 61, 65 

sieve element, 11 

sieve cell, 8, 11 

sieve tube element, 8, 11, 18 

silica cell, 10, 22 

somatic (vegetative) cell, 6, 30 

subsidiary cell, 10, 22 

synergid cell, 32, 37 

tracheary element, 11 

tracheid, 8, 11, 17 

vessel element, 8, 11, 17 

Cellulose, 2, 8 

Celtis tenuifolia, 82 

Centaurea, 4 

Cephalaria, 118 

Cerastrium, 87 

Ceratium, 55 

Ceratocystis ulmi, 48, 82 

Cercis, 100 

Ceropegia woodii, 110 

Cetarias, 54

Chaetomium, 48 

Chamaecyparis, 73 

Chamaedorea, 125, 126 

Chamaerops, 125 

Chantharellus, 51 

Chara, 62 

Charophyta, 41, 62 

Cheeses, 90 

Chenille plant, 103 

Chenopodiaceae, 88 

Chenopodium, 26, 89 

Cherry, 39, 99 

Chervil, 109 

Chestnut, 35, 83 

Chestnut blight, 48, 83 

Chichorium, 119 

Chick pea, 100 

Chickweed, 87 

Chicory, 119 

Chinese anise, 77 

Chinese elm, 82 

Chinese evergreen, 127 

Chinese lantern, 111 

Chinese water chestnut, 122 

Chinese windmill palm, 125 

Chionanthus, 114 

Chitin, 46 

Chives, 128 

Chlamydomonas, 58 

Chloroplast, 2, 3,10,13, 22, 24, 55, 56, 

58, 59 

Chlorophyll, 3, 4, 24, 47, 56, 57, 58, 59, 

62, 66 

chlorophyll a, 4, 24, 45, 55, 56, 57, 58, 

59, 62 

chlorophyll b, 4, 58, 62 

chlorophyll c, 4, 55, 56, 59 

chlorophyll d, 4, 57 

Choanephora, 47 

Chondrus, 57 

Christmas rose, 80 

Christmas vine, 112 

Chromosomes, 2, 6, 7, 30, 55 

crossing-over (chiasma), 6, 30 

diploid (2n), 6, 30, 37, 59, 61, 64, 67 

haploid (1n), 6, 30, 31, 37, 59, 61, 63, 

64, 67 

Chrysophyceae, 56 

Chysalidocarpus, 125 

Chysanthemum, 19, 26, 119 

Cibotium, 67 

Cicer, 100 

Cicuta maculata, 109 

Cimicifuga, 80 

Cinnamomum, 78 

Cinnamon, 78 

Cirsium, 119 

Cissus, 104 

Citron, 94, 107 

Citrullus lanatus, 94 

Citrus, 39, 107 

Cladonia, 54 

Cladophora, 58 

Clathrus, 53 

Claviceps, 48 

Clavulinopsis, 52 

Clematis, 16, 80 

Clover, 12, 26, 33, 100 

Clubmosses, 41, 42, 65 

Coccoloba uvifera, 89 

Cocklebur, 26, 119 

Coco-de-mer, 125 

Coconut palm, 125 

Cocothrinax argentea, 125 

Codiaeum, 103 

Colchicine, 128 

Colchicum, 128 

Coleus, 19, 113 

Collinea, 126 

Colocasia, 127 

Columbine, 80 

Columnea, 116 

Commelina, 121 

Commelinaceae, 121 

Commelinidae, 75 

Common blue violet, 92 

Common mallow, 90 

Common rue, 107 

Common toadflax, 115 

Cone, 38, 71, 73, 74 

Coneflower, 26, 119 

Conifer, 8, 9, 12, 13, 15, 21, 22, 33, 38, 

40, 41, 42, 50, 63, 71, 73, 76 

Conium maculatum, 109 

Convallaria majalis, 128 

Convolvulaceae, 112 

Convolvulus, 112 

Copernicia, 125 

Coprinus, 51 

Coquitos palm, 125 

Coral bells, 98 

Corallina, 57 

Coral plant, 115 

Coral-sumac, 106 

Cordaites, 42 

Coriander, 109 

Coriandrum sativum, 109 

Coriolus, 52 

Cork, 9, 10, 15, 22 

Cork tree, 107 

Corm, 12, 16, 18, 65, 128, 129 

Corn, 12, 19, 24, 40, 123 

Cornaceae, 101 

Corn cockle, 87 

Cornelian cherry, 101 

Cornflower, 4 

Cornus, 101 

Cortinarius, 50 

Corylopsis, 81 

Corylus, 84 

Coscinodiscus, 56 

Cotinus coggygria, 106 

Cotton, 10, 90 

Cottonwood, 95 

Cow cockle, 87 

Cow-parsnip, 109 

Cranberry, 97 

Crane’s-bill, 109 

Crataegus, 99 

Crocus, 16, 129 

Cronartium, 49 

Croton, 103 

Crown-of-thorns, 103 

Crucibulum, 53 

Cucumber, 39, 94 

Cucumber tree, 77 

Cucumis, 39, 94 

Cucurbita, 94 

Cucurbitaceae (Gourd Family), 39, 94 

Cumin, 109 

Cuminum cyminium, 109 

Cup-of-gold, 111 

Cupressus, 73 

Curled dock, 38 

Curled mallow, 90 

Curly palm, 125 

Currant, 98, 104 

Cuscuta, 112 

Cutin, 2,10,13, 22 

Cut-leaf philodendron, 127 

Cyanobacteria, 41, 44 

Cyanotis, 121 

Cyathus, 53 

Cycads, 41, 42, 44, 71, 72 

Cycadophyta, 41, 71 

Cydonia, 99 

Cylindrospermum, 44 

Cymbalaria, 115 

Cymbidium, 130 

Cynara scolymus, 119 

Cynodon, 123 

Cyperaceae, 122 

Cyperus, 122 

Cypress, 73 

Cypress spurge, 88 

Cypress vine, 112 

Cyrtomium, 67 

Cytokinin, 19 

Dacryopinax, 49 

Dactylis, 123 

Dahlia, 12, 119 

DaIdinia concentrica, 48 

Dandelion, 119 

Darlingtonia, 91 

Date palm, 125 

Datura, 111 

Daucus carota (carrot), 4, 12, 38, 109 

Dayflower, 121 

Day lily, 128 

Deadly nightshade, 111 

Dead man’s finger, 48 

Death camas, 128 

Delonix, 100 

Delphinium, 4,80 

Dendrobium, 130 

Deptford-pink, 87 

Destroying angel, 50 

Deuteromycota, 46 

Deutzia, 98 

Devil’s-ivy, 127 

Diachea, 45 

Dianthus, 75, 87 

Diatom, 4, 41, 56 

Diatrypella, 48 

Dichondra, 112 

Dichorisandra, 121 

Dicot (dicotyledon), 1, 9, 12, 13, 14, 15, 

19, 21, 22, 27, 31, 37, 74, 75, 

77–119 

Dictamnus, 107 

Dictydium, 45 

Dictyophora, 53 

Didymium, 45 

137

Dieffenbachia, 127 

Digitalis purpurea, 115 

Dill, 26, 109 

Dilleniidae, 75 

Dinobryon, 56 

Dinoflagellates, 41, 55 

Dioecious condition, 28, 35, 60, 63, 71, 

72, 73, 74, 78, 95, 105 

Dionaea, 23 

Dioön edule, 71 

Dipsacaceae, 118 

Dipsacus, 118 

Dipteronia, 105 

Diseases of plants, 43, 46, 47, 48, 49, 82, 

83 

Dittany, 107 

DNA (deoxyribonucleic acid), 2, 3, 6, 7, 

24, 41, 43, 44 

Doctor gum, 106 

Dodder, 112 

Dogtooth lily, 128 

Dogwood Family, 101 

Douglas fir, 73 

Draba, 96 

Dracaena, 15 

Drosera, 23 

Drymaria pachyphyua, 87 

Dryopteris carthusiana (spinulosa), 68 

Duckweed, 75 

Dulse, 57 

Dumb-cane, 127 

Dusty miller, 87 

Dutch elm disease, 82 

Dwarf chinkapin oak, 83 

Dwarf hackberry, 82 

Dyer’s woad, 96 

Ear fungus, 49 

Earth star, 53 

Earth tongue, 48 

Echinodorus, 120 

Echinopsis, 85 

Ecosystem, 43, 44, 45, 54, 56, 57, 58, 59 

Ectocarpus, 59 

Edelweiss, 119 

Egg, 27, 30, 32, 37, 46, 56, 59, 60, 61, 

62, 63, 64, 66, 67, 71 

Elaeis guineesis, 125 

Elaeodendron, 102 

Elderberry, 117 

Eleocharis tuberosa, 122 

Elephant’s-ear, 127 

Elm, 35, 38, 82 

Elm Family, 35, 82 

Encyclia, 16 

Endiandra, 78 

Endive, 119 

Endothia parasitica, 48, 83 

English oak, 83 

Enzyme, 2, 3, 4, 10 

Ephedra, 74 

Epidendrum, 130 

Epiphyte, 16, 20, 59, 64, 67, 76, 130 

Episcia, 116 

Equisetum, 15,16, 20, 43, 66 

Ergot of rye, 48 

Erica, 97 

Ericaceae, 97 

138 

Erodium, 108 

Eryngium, 109 

Erythea, 125 

Erythronium, 128 

Eucalyptus, 75 

Eudorina, 58 

Euonymus, 102 

Eupatorium rugosum, 119 

Euphorbia, 23, 26,103 

Euphorbiaceae (Spurge Family), 16, 103 

European fan palm, 125 

European spindle-tree, 102 

European white birch, 84 

Evernias, 54 

Fabaceae (Pea Family), 34, 39, 100 

Fagaceae (Beech Family), 35, 83 

Fagopyrum, 89 

Fagus, 83 

Fairy ring mushroom, 50 

False cypress, 73 

False dragonhead, 113 

False goat’s-beard, 98 

False hellebore, 128 

False Iily-of-the-valley, 128 

False mallow, 90 

False sandalwood, 82 

False Solomon’s seal, 128 

Fan palm, 125 

Fanwort, 79 

Fennel, 109 

Ferns, 8, 41, 42, 44, 67, 68, 69, 70 

Fertilization, 27, 33, 34, 37, 62, 63, 64, 

65, 66, 67, 71 

Festuca, 123 

Festue grass, 123 

Figwort, 115 

Figwort Family, 115 

Filbert, 84 

Fir, 73, 76 

Firethorn, 99 

Fishtail palm, 125, 126 

Flag, 34, 129 

Flagellum, 43, 44, 45, 46, 55, 56, 57, 58, 

60, 61, 62, 63, 64, 65, 71 

Flamingo flower, 75, 127 

Flame plant, 127 

Flat palm, 125 

Flower arrangement (inflorescence), 19, 

27, 33, 35 

catkin (ament), 35, 75, 83, 95 

cyme, 84, 102, 108, 111 

fleshy spike (spadix), 34, 75, 127 

head (capitulum), 33, 75, 118, 119 

panicle, 106, 114,124,125, 126 

raceme, 96, 100, 120 

single (scapose), 80, 85, 87, 90, 91, 

92, 112 

spike, 88, 115, 122, 123 

umbel, 109, 110 

Flowering dogwood, 101 

Flowering maple, 90 

Flowering plants, 1, 30, 31, 33, 41, 75, 

77–130 

Flower structure, 27, 28, 33, 34 

androecium, 27 

calyx, 27, 34 

corolla, 27, 33 

gynoecium, 27 

nectaries, see Nectar 

perianth, 27, 75 

petals, 10, 27, 28, 29, 33, 34, 35, 36, 

75 

bilabiate, 34, 36, 113, 115, 116, 117 

cruciform, 96 

funnelform, 34, 112 

pistil (stigma, style, ovary), see Pistil 

structure 

placenta, 27, 28, 32, 111 

receptacle, 27, 29, 99, 120 

sepals, 27, 28, 29, 33, 35, 75 

stamen (anther, filament, connective), 

see Stamen structure 

staminoids, 78, 116, 124 

tepals, 1, 26, 27, 36, 76, 85, 86, 89, 93, 

127, 128 

Flower symmetry, 34, 75 

Flower types 

bisexual (perfect), 28, 33, 35, 36, 75, 

78, 79, 80, 81, 82, 86, 87, 88, 89, 

90, 91, 97, 99, 101, 102, 107, 108, 

114, 115, 117, 119, 121, 122, 123, 

124, 126, 127, 130 

complete, 28 

dicot, 27, 77–119 

incomplete, 28 

monocot, 27, 120–130 

unisexual (imperfect), 28, 33, 35, 75, 

83, 84, 93, 94, 95, 103, 104, 105, 

106, 119, 120, 125, 127 

Fly agaric, 50 

Fly amanita, 50 

Foeniculum vulgare, 109 

Fomes, 52 

Fool’s huckleberry, 97 

Forsythia, 114 

Fortunella, 107 

Fossils, 42 

Fothergilla, 81 

Foxglove, 115 

Foxtail grass, 123 

Fragaria (strawberry), 20, 26, 39, 99 

Fragrant olive, 114 

Fraxinella, 107 

Fraxinus, 99, 114 

Freesia, 129 

Fringe tree, 114 

Fritillaria, 128 

Fruiting body, 45, 46, 47, 48, 49, 50, 51, 

52, 53, 54 

aethalium, 45 

ascocarps: 

apothecium, 48, 54 

cleistothecium, 48 

perithecium, 48 

basidiocarps: 

bird’s-nest, 53 

coral, 50, 52 

earthstar, 53 

mushroom, 49, 50, 51 

puffball, 49, 53 

shelf, 49, 50, 52 

stinkhorn, 53 

toothed, 50, 52 

plasmodiocarp, 45 

sporangium, 45

Fruit (ovary wall) tissues, 38, 39 

endocarp, 39, 107 

exocarp, 39, 107 

mesocarp, 8, 39, 97, 107 

pericarp, 38, 39, 40, 94, 123 

Fruit types, 38, 39 

achene, 38, 39, 80, 89, 118, 119, 122 

berry, 39, 79, 86, 98, 104, 111, 117, 

127 

capsule, 38, 81, 87, 90, 92, 93, 95, 98, 

102, 108, 114, 121, 128, 129, 

130 

cypsela, 38 

drupe, 39, 78, 82, 97, 101, 106, 114, 

125, 126 

drupelet, 39 

follicle, 38, 77, 110 

grain (caryopsis), 3, 19, 38, 40, 48, 123 

hesperidium, 39, 107 

legume, 8, 38, 100 

loment, 38, 100 

mericarp, 38, 90, 109 

nut, 8, 38, 83 

nutlet, 38, 88, 97, 113 

pepo, 39, 94 

pome, 39, 99 

samara, 38, 82, 84, 105, 114 

schizocarp, 38, 90, 103, 109 

silicle, 38, 96 

silique, 38, 96 

Fuchsia, 4, 20, 36 

Fucus, 61 

Fullmoon maple, 105 

Fungi, 1, 12, 24, 41, 45, 46, 47, 48, 49, 

50, 51, 52, 53, 54, 64, 82, 83 

Fungi Kingdom 

Ascomycetes, 47, 48, 54, 82, 83 

Euascomycetidae (molds, wilts, 

blight, mildews), 48 

Hemiascomycetidae (yeast, peach 

leaf curl), 47 

Basidiomycetes, 49, 50, 51, 52, 53, 54 

Agaricales (gill, pore, coral, toothed 

fungi), 50, 51, 52 

Auriculariales (jelly fungi), 49 

Dacrymycetales (jelly fungi), 49 

Lycoperdales (puffball fungi), 53 

Nidulariales (bird’s-nest fungi), 53 

Phallales (stinkhorn fungi), 53 

Tremellales (jelly fungi), 49 

Uredinales (rusts), 49 

Ustilaginales (smuts), 49 

Chytridiomycetes (chytrids & allies), 46 

Myxomycetes (slime molds), 45 

Oomycetes (water molds, downy 

mildews, white rusts), 46 

Zygomycetes (black bread mold & 

allies), 47 

Gaillardia, 119 

Galaxaura, 57 

Gametophyte, 31, 32, 40, 57, 59, 60, 61, 

63, 64, 65, 66, 67, 72 

Ganoderma, 50 

Garlic, 128 

Gas-plant, 107 

Gaultheria, 97 

Gaylussacia, 97 

Gazania, 119 

Geastrum, 53 

Gelidium, 57 

Geoglossum, 48 

Geologic time scale, 41, 42 

Geraniaceae, 108 

Geranium, 108 

Geranium, 4, 108 

Geranium Family, 108 

Gesneria Family, 116 

Gesneriaceae, 116 

Giant sequoia, 73 

Giant water lily, 79 

Gibasis geniculata, 121 

Ginger Family, 124 

Ginkgo, 16, 21, 41, 71, 72 

Ginkgophyta, 41, 42, 72 

Gladiolus, 16, 129 

Gleditsia, 100 

Gloetrichia, 44 

Gloiopeltis, 57 

Gloriosa, 128 

Gloriosa lily, 16, 128 

Gloxinia, 116 

Glycine, 100 

Gnetes, 41, 42, 71, 74 

Gnetophyta, 41, 74 

Gnetum, 74 

Golden Algae, 41, 56 

Golden bells, 114 

Golden-chain tree, 100 

Golden club, 127 

Goldenrod, 38, 119 

Golden seal, 80 

Goldfish plant, 116 

Gonyaulax, 55 

Gooseberry, 98 

Gossypium hirsutum, 90 

Gourd, 94 

Gourd Family, 39, 94 

Goutweed, 109 

Grape, 16, 39, 104 

Grape Family, 104 

Grapefern, 67 

Grapefruit, 107 

Grape-hyacinth, 128 

Grape ivy, 104 

Graphis, 54 

Grass Family, 10, 15, 19, 22, 23, 24, 35, 

38, 76, 122, 123, 125 

Green Algae, 4, 41, 54, 58, 62 

Green ash, 114 

Greenbriar, 16, 128 

Greenheart, 79 

Green violet, 92 

Grey dogwood, 102 

Griselinia, 102 

Ground cherry, 111 

Growth 

primary, 9, 13, 15 

secondary, 9, 12, 13, 14, 15, 65, 67, 71 

Growth movements, 20 

Growth rings, 15 

Gymnocladus, 100 

Gymnodinium, 55 

Gymnosperm, 41, 71, 72, 73, 74 

Gymnosporangium, 49 

Gymnosporia, 102 

Gypsophila, 87 

Gyromitra, 48 

Haberlea, 116 

Hackberry, 35, 82 

Hair (trichome), 8, 9, 10, 13, 17, 22, 23, 

44, 67, 70, 77, 81, 85, 86, 88, 90, 

91, 94, 95, 97, 98, 106, 111, 116, 

117, 129 

Hamamelidaceae, 81 

Hamamelidae, 75 

Hamamelis, 81 

Hapalosiphon, 44 

Haworthia, 128 

Hawthorn, 49, 99 

Hazelnut, 35, 84 

Heath, 97 

Heath Family, 97 

Hedera, 16 

Hedge bindweed, 112 

Helenium, 119 

Heliamphora, 91 

Helianthus 

annuus, 19, 119 

tuberosus, 119 

Helichrysum, 119 

Helicodicerus, 127 

Helleborus, 80 

Helminthostachys, 67 

Helwingia, 101 

Helvella, 48 

Hemerocallis, 128 

Hemitrichia, 45 

Hemlock, 73, 109 

Hepatica, 80 

Heracleum, 109 

Hericium, 52 

Herpobasidium, 49 

Hesperis, 96 

Heterospory, 65, 70 

Heuchera sanguinea, 98 

Hevea brasiliensis, 103 

Hibiscus 

esculentus, 90 

rosa-sinensis, 29 

syriacus, 26 

Hillebrandia, 93 

Hoary cress, 96 

Holly fern, 67 

Hollyhock, 49, 90 

Hollyhock mallow, 90 

Homospory, 64, 65, 66 

Honesty, 38, 96 

Honey-dew melon, 94 

Honey locust, 100 

Honey mushroom, 50 

Honeysuckle, 117 

Honeysuckle Family, 117 

Hop-hornbeam, 84 

Hop tree, 107 

Hordeum vulgare, 26, 123 

Hormones, 19, 20, 24, 26 

Hornwort, 42, 63 

Horse-bush, 119 

Horse-radish, 96 

Horsetails, 41, 42, 66 

Hosta, 128 

Howeia, 125 

139

Hoya carnosa, 110 

Huckleberry, 97 

Huernia, 110 

Hyacinth, 128 

Hyacinthus, 128 

Hybanthus, 92 

Hybrid, 1, 6, 77 

Hydrangea, 98 

Hydrastis, 80 

Hypha, 12, 46, 47, 48, 50, 54 

Iberis, 96 

Illicium vernum, 77 

Inch plant, 121 

Indian paint-brush, 115 

Indian pipe, 97 

Ipomoea 

batatas, 12, 112 

pandurata, 12 

purpurea, 112 

tuberosa, 16, 112 

Iridaceae (Iris Family), 34, 129 

Iris, 16, 34, 129 

Iris Family, 34, 129 

Irpex, 52 

Irish moss, 57 

Ironwood, 35 

Isatis tinctoria, 96 

Isoetes, 65 

Ivy, 12, 16 

Ixia, 129 

Jack-in-the-pulpit, 127 

Japanese dogwood, 101 

Japanese honeysuckle, 117 

Japanese lacquer-tree, 106 

Japanese laurel, 101 

Jasmine, 114 

Jasminum, 114 

Jerusalem artichoke, 119 

Jerusalem-cherry, 111 

Jimson weed, 111 

Jubaea spectabilis, 125 

Juncaceae, 35 

Juniper, 49, 73 

Juniperus (cedar, juniper), 49, 73 

Kale, 96 

Kalmia, 97 

Kapuka, 101 

Kelp, 15, 59, 60 

Kenilworth ivy, 115 

Kentucky coffee tree, 100 

Kinnikinik, 97 

Kniphofia, 128 

Knotweed, 89 

Kochia, 88 

Kohleria, 116 

Kohlrabi, 96 

Kolkwitzia, 117 

Kudzu vine, 100 

Kumquat, 107 

Laburnum, 100 

Lactuca sativa, 119 

Lady palm, 125 

Lady’s thumb, 89 

Laelia, 130 

140 

Lagenaria, 94 

Lambkill, 97 

Lamb’s quarters, 26, 88 

Lamiaceae (Mint Family), 34, 113 

Laminaria, 60 

Larch, 73 

Larkspur, 4, 80 

Larix, 73 

Latex, 11, 79, 103, 110, 112 

Lathyrus latifolia, 100 

Lauraceae, 78 

Laurel Family, 78 

Laurus nobilus, 78 

Lavandula, 113 

Lavatera, 90 

Lavender, 113 

Leaf arrangement 

alternate, 21, 72, 81, 88, 93, 95, 97, 

102, 104, 110, 112, 115, 121, 123, 

124 

decussate, 87 

equitant, 129 

opposite, 21, 74, 87, 102, 105, 113, 

114, 116, 117, 118 

spiral, 65, 71 

rosette, 63, 65, 91, 109, 116 

whorled, 21, 74, 128 

Leaf, blade margin 

entire, 77, 78, 101, 114, 116, 121 

lobed, 67, 70, 72, 78, 79, 83, 90, 94, 

104, 108, 111, 120 

peltate, 79 

saw-toothed (serrate), 80, 82, 84 

scalloped (crenate), 92 

toothed (dentate), 80, 83, 95, 99, 102, 

105 

Leaf, external structure, 21 

blade, 21, 23 

cuticle, 17, 22 

coleoptile, 20, 40 

leaflet (pinna, pinnule), 21, 23, 33, 67, 

68, 69, 70, 71, 80, 100, 106, 109, 

125, 126, 127 

petiole (stalk), 8, 14, 21, 22, 23, 68, 69, 

70, 71 

pulvinus, 100, 124 

sheath (petiole), 21, 66, 109, 120, 121, 

123, 124, 127, 129, 130 

stipule, 16, 23, 77, 84, 89, 90, 92, 93, 

99, 100, 102, 108 

Leaf persistence 

deciduous, 21, 72, 76 

evergreen, 21, 65, 68, 76 

Leaf types, 21, 23, 40 

bract, 23, 29, 33, 34, 36, 38, 75, 77, 

83, 87, 93, 95, 101, 103, 109, 112, 

117, 118, 119, 122, 123, 124, 126, 

129 

carnivorous leaf, 23 

conifer leaf, 15, 21, 22 

dicot leaf, 21, 37, 40, 77–119 

compound leaf, 21, 35, 67, 68, 69, 70, 

71, 100, 106, 109, 125, 126, 127 

fern leaf, 67, 68, 69, 70 

microphyll, 65 

megasporophyll, 65, 71 

microsporophyll, 65, 71 

sporophyll, 66, 71 

monocot leaf, 1, 21, 40, 120–130 

phyllode, 23 

plumule, 40 

scale leaf, 12, 16, 85 

seed leaf (cotyledon), 1, 8, 37, 40, 72, 

75 

simple leaf, 21, 67, 77, 79, 81, 83, 

84, 85, 97, 101, 103, 107, 108, 

110, 111, 112, 113, 114, 117, 

130 

spathe, 23, 127 

spine, 23, 36, 85, 103 

succulent leaf, 23 

Leaf venation 

dichotomous, 21, 71, 72 

palmate, 21, 67, 90, 93, 94, 105, 108, 

125 

parallel, 21, 120, 121, 123, 128 

pinnate, 21, 67, 68, 125, 126 

Leatherleaf fern, 69 

Leatherleaf, 97 

Leek, 128 

Lemon, 39, 107 

Lens, 100 

Lentil, 100 

Leonotis, 113 

Leontopodium, 119 

Leopard lily, 128 

Lepidium, 96 

Lepidodendron, 43 

Letharia, 54 

Lettuce, 119 

Leucothoë, 97 

Levisticum officinale, 109 

Lichen, 44, 54, 76 

Light wavelength, 4, 34 

Lignin, 8, 10, 23, 125 

Ligustrum, 114 

Lilac, 14,114 

Liliaceae, 1, 15,128 

Lilidae, 75 

Liliopsida, 1, 75,120–130 

Lilium michiganense, 1, 38, 128 

Lily, 1, 38,128 

Lily-of-the-valley, 128 

Lily Family, 1, 15, 128 

Lime, 107 

Linaria vulgaris, 115 

Lindera benzoin, 78 

Linnaea borealis, 117 

Linnaeus, Carolus, 41 

Lion’s-ear, 113 

Lipstick plant, 116 

Liquidambar styraciflua, 81 

Liriodendron tulipifera, 77 

Lithocarpus, 83 

Lithops, 23 

Lithothamnium, 57 

Litsea, 78 

Liverwort, 41, 44, 63 

Living stones, 23 

Livistona, 125 

Lobularia maritima, 75, 96 

Locoweed, 100 

Locule, 27, 31, 32 

Locust, 38, 100 

Lodoicea maldivica, 125 

Loganberry, 99

Lolium perenne, 26 

Lonicera, 117 

Loofah, 94 

Loropetalum, 81 

Lousewort, 115 

Lovage, 109 

Luffa cylindria, 94 

Lunaria annua, 38, 96 

Lupine, 100 

Lupinus, 100 

Lychnis, 87 

Lycogala, 45 

Lycoperdon, 53 

Lycopersicon esculentum (tomato), 3, 4, 

111 

Lypodium, 65 

Lyonia mariana, 97 

Maclura pomifera, 39 

Madagascar featherpalm, 125 

Madagascar-jasmine, 110 

Magnolia, 75, 77 

Magnoliidae, 75 

Magnoliaceae, 77 

Magnolia Family, 77 

Magnoliophyta, 1, 75 

Magnoliopsida, 1, 75, 77–119 

Maianthemum, 128 

Maiden hair fern, 67, 72 

Maiden hair tree, 72 

Majorana, 113 

Mallow Family, 90 

Malope, 90 

Maltese cross, 87 

Malus (apple), 4, 16, 31, 39, 49, 75, 99 

Malvaceae, 90 

Malva, 90 

Mammillaria, 85, 86 

Mangifera indica, 106 

Mango, 106 

Mangrove, 12 

Manihot, 103 

Manroot, 12 

Maple, 26, 35, 38, 105 

Maple Family, 35, 105 

Maranta, 124 

Marantaceae, 124 

Marasmius, 50 

Marchantia, 63 

Marigold, 75, 119 

Marjoram, 113 

Marsilea quadrifolia, 70 

Marsh marigold, 80 

Mastic tree, 106 

Matthiola, 96 

Maytenus, 102 

Meadow rue, 80 

Medicago, 12, 38, 100 

Meiosis, 30, 31, 32, 45, 46, 61, 63 

Melilotus, 100 

Melocactus, 85 

Melon, 94 

Mentha, 38, 113 

Menziesia ferruginea, 97 

Mercurialis, 103 

Mercury, 103 

Meristem, 9, 11, 13, 14, 15, 25, 40, 60, 

66, 69, 71, 74 

apical meristem, 9, 11, 13, 14, 15, 25, 

40 

cork cambium, 9, 13, 15 

ground meristem, 13, 15 

intercalary meristem, 15, 66, 74 

procambium, 9, 11, 13, 14, 15 

protoderm, 13, 15 

vascular cambium, 9, 13, 15 

Metopium toxiferum, 106 

Metroxylon, 125 

Mexican fan palm, 125 

Michelia fuscata, 77 

Michigan lily, 1, 38, 128 

Microasterias, 58 

Microglossum, 48 

Microsphaera, 48 

Milkweed, 38, 110 

Milkweed Family, 110 

Millet, 123 

Miltonia, 130 

Mimosa, 38, 100 

Mimulus, 115 

Miniature hollyhock, 90 

Mint, 38, 113 

Mint Family, 113 

Mitella, 98 

Mitosis, 7, 30, 31, 32, 45 

Mock orange, 98 

Molucella, 113 

Monarda, 113 

Money plant, 96 

Monera, 41 

Monilinia, 48 

Monkey-flower, 115 

Monkshood, 80 

Monocot (monocotyledon), 1, 9, 11, 12, 

13, 15, 21, 22, 27, 31, 35, 40, 75, 

120–130 

Monoecious condition, 28, 70, 73, 74, 83, 

84, 93, 94, 104 

Monotropa, 97 

Monstera deliciosa, 127 

Moonflower, 112 

Morel, 48 

Morchella, 48 

Morina, 118 

Morning glory, 112 

Morning Glory Family, 112 

Moses-in-the-cradle, 121 

Mosquito fern, 67, 70 

Moss, 41, 51, 63 

Mother-of-thousands, 98 

Moth orchid, 75 

Mountain ash, 99 

Mountain laurel, 97 

Mountain-rose vine, 89 

Mouse-ear chickweed, 87 

Mucor, 47 

Mullein, 115 

Murraya, 107 

Musaceae, 124 

Muscari, 128 

Musk mallow, 90 

Mustard, 38, 96 

Mustard Family, 38, 96 

Mutinus, 53 

Mutualist (symbiont), 12, 44, 46, 54, 55 

Mycelium, 46, 47, 48, 49 

Mycophycophyta, 54 

Mycorrhizae, 12, 46, 50, 64, 97, 130 

Myrrhis odorata, 109 

Myxomycetes, 45 

Nannyberry, 117 

Narcissus, 31 

Nasturtium, 96 

Neathe bella, 126 

Nectar, 33, 34, 36, 47, 99, 109, 115 

Nectar gland, disc, 8, 10, 23, 33, 34, 35, 

36, 75, 81, 94, 95, 96, 97, 101, 

103, 104, 106, 107, 108, 109, 112, 

115, 116, 129 

osmophor, 10 

Nectar guide, 33, 34, 92, 116, 130 

Nectar spur, 33, 34, 36, 92, 115 

Nectar tube, 33, 34, 130 

Neddle palm, 125 

Nemopanthus, 116 

Neoporteria, 85 

Nepeta, 113 

Nephrolepis, 67 

Nereocystis, 60 

Neurospora, 48 

New Zealand spinach, 88 

Nicotiana, 34, 111 

Nidularia, 53 

Nierembergia, 111 

Nightshade Family, 111 

Ninebark, 99 

Nitrogen, 12, 23, 25, 43, 70, 100 

Nitrogen fixation, 12, 25, 43, 44, 100 

Nori, 57 

Norway maple, 105 

Nucleic acid, 24 

Nucleoid, 6, 43 

Nucleolus, 2, 7, 58 

Nucleoplasm, 2 

Nucleus, 2, 3, 5, 6, 7, 30, 31, 32, 37, 41, 

45, 58 

Nuphar, 79 

Nutrients, 25 

Nymphaeaceae, 79 

Nymphaea, 79 

Oak, 17, 35, 38 

Oats, 19, 20, 26, 49, 123 

Ochrolechia, 54 

Ocimum, 113 

Ocotea, 78 

Odontoglossum, 130 

Oil palm, 125 

Okra, 90 

Olea, 114 

Oleaceae, 114 

Olive, 114 

Olive Family, 99, 114 

Oncidium, 130 

Onion, 16, 49, 128 

Onoclea, 67 

Ophioglossum, 67 

Opuntia, 16, 85 

Orange jessamine, 107 

Orchard-grass, 123 

Orchid, 16, 75, 130 

Orchidaceae, 130 

Orchid Family, 130 

141

Orchid tree, 100 

Oregano, 113 

Oriental walnut, 78 

Origanum, 113 

Ornithogalum umbellatum, 128 

Orontium, 127 

Oryza sativa (rice), 3, 19, 26, 38, 70, 123 

Osage-orange, 39 

Osmanthus, 114 

Osmosis, 5,18 

Osmunda, 67 

Ostrya, 84 

Oswego tea, 113 

Otaheite gooseberry, 103 

Oxypetalum caeruleum, 110 

Oyster mushroom, 50 

Pachystima, 102 

Paeonia, 80 

Palm, 15, 25, 125 

Palmaria, 57 

Palm Family, 125, 126 

Pansy, 92 

Papaver, 38 

Paper birch, 84 

Paphiopedilum, 130 

Paprika, 111 

Parasite, 46, 47, 49, 54, 55, 112, 115 

Parlor palm, 125, 126 

Parmelia, 54 

Parsley, 109 

Parsnip, 109 

Parthenocissus 

quinquefolia, 16, 104 

tricuspidata, 104 

Pastinaca sativa, 109 

Pea, 12, 40, 100 

Peaberry palm, 125 

Peach, 99 

Pea Family, 34, 38, 100 

Peanut, 15, 100 

Pear, 8, 49, 99 

Peat moss, 63 

Pedicularis, 115 

Pelargonium, 4,108 

Peltandra, 127 

Penicillium, 48 

Penny cress, 96 

Pepper-grass, 96 

Perennial, 12, 14, 21, 64, 65, 66, 67, 68, 

79, 80, 86, 88, 91, 92, 93, 96, 98, 

100, 108, 110, 111, 112, 113, 115, 

120, 121, 122, 123, 124, 127, 128, 

129, 130 

Pereskia grandifolia, 85 

Persea, 78 

Petroselinum crispum, 109 

Petunia, 26, 111 

Phaeophyta, 41, 59, 60, 61 

Phalaenopsis, 75, 130 

Phallus, 53 

Phaseolus (bean), 12, 14, 40, 100 

Philadelphus, 98 

Philodendron, 16, 127 

Phleum, 123 

Phloem, 8, 9, 11, 13, 15, 17, 18, 22, 24, 

42 

Phoenix dactylifera, 125 

142 

Photosynthesis, 3, 4, 5, 8, 24, 40, 41, 44, 

60, 63, 85 

Phyllanthus, 103 

Phellodendron, 107 

Physalis, 111 

Physarum cinereum, 45 

Physcia, 54 

Physocarpus, 99 

Physoderma, 46 

Physostegia, 113 

Phytophthora infestans, 46 

Picea, 73 

Pieris, 97 

Pigments, 2, 3, 4, 24, 44 

accessory pigments, 4, 24, 44 

betalains, 4, 76, 87, 88 

betacyanin, 4, 75 

betaxanthin, 4, 75 

carotenoids, 3, 4, 10 

carotene, 4, 44, 55, 56, 57, 58, 59, 

62 

xanthophylls, 3, 4, 55, 57, 58, 62 

fucoxanthin, 4, 56, 59 

leutein, 4 

peridinin, 55 

violaxanthin, 4, 59 

zeaxanthin, 4 

chlorophylls, see Chlorophyll 

flavinoids, 4 

anthocyanin, 4, 25, 87 

flavin, 4 

riboflavin, 4 

phycobilins, 4, 57 

phycocyanin, 4, 44, 57 

phycoerythrin, 4, 44, 57 

phytochrome, 4 

Pimpinella anisum, 109 

Pincushion cactus, 85, 86 

Pincushion flower, 118 

Pine, 41, 49, 73, 76 

Pinophyta, 41, 73 

Pinguicula, 10, 23 

Pink, 75, 87 

Pink Family, 87 

Pinnularia, 57 

Pinus, 40, 73 

Pistachio, 106 

Pistacia, 106 

Pistia, 126 

Pistil structure, 27, 28, 29, 32, 33, 37, 38, 

77–130 

carpel, 27, 28, 29, 32, 35, 38, 39, 75, 

79, 80, 92, 93, 94, 99, 101, 102, 

103, 105, 108, 109, 110, 111, 

112, 113, 114, 115, 121, 128, 

129 

ovary, 27, 28, 29, 32, 33, 35, 36, 37, 

38, 39, 75, 77, 78, 79, 82, 90, 92, 

93, 95, 97, 99, 101, 105, 109, 110, 

113, 114, 116, 118, 119 

ovary placentation, 27, 28, 32, 75 

axile, 28, 81, 91, 97, 114, 128, 129 

basal, 28, 75, 120, 127 

free-central, 28, 75, 87 

parietal, 28, 75, 86, 92, 94, 98, 100, 

110 

ovary position, 28, 33 

haif-inferior, 28, 81, 116 

inferior, 28, 33, 38, 39, 75, 84, 86, 

93, 94, 98, 99, 101, 109, 116, 117, 

118, 119, 124, 129, 130 

superior, 28, 29, 33, 38, 75, 77, 78, 

82, 87, 88, 90, 91, 96, 97, 100, 

102, 103, 104, 105, 107, 109, 111, 

112, 113, 114, 115, 116, 121, 122, 

123, 126, 128 

ovule, 27, 28, 29, 30, 32, 37, 40, 75, 

78, 79, 80, 86, 87, 90, 91, 92, 93, 

94, 95, 97, 98, 99, 100, 101, 106, 

109, 110, 111, 112, 114, 115, 118, 

119, 122, 123, 126, 129 

antipodal cells, 32 

egg, 27, 30, 32, 37 

embryo sac, 27, 30, 32, 37 

endosperm, 37, 40, 75, 123 

filiform apparatus, 32 

funiculus, 32, 40 

integument, 32, 37, 40, 75 

micropyle, 32, 37, 40 

nucellus, 32 

polar nuclei, 32, 37 

synergid cells, 32, 37 

stigma, 27, 29, 32, 33, 35, 36, 37, 81, 

85, 86, 91, 92, 93, 96, 97, 98, 99, 

100, 101, 103, 106, 107, 108, 110, 

111, 112, 113, 114, 115, 116, 117, 

118, 120, 121, 124, 128, 129, 130 

branched, 86, 122 

capitate, 96, 104 

double (bifurcate), 95, 98, 103, 113 

feathery (plumose), 35, 82, 87, 105, 

123 

style, 27, 29, 32, 33, 36, 37, 77, 81, 84, 

86, 88, 91, 95, 97, 98, 99, 100, 

101, 103, 108, 109, 111, 112, 113, 

114, 115, 117, 118, 119, 120, 121, 

124, 128, 129 

Pisum, 12, 40, 100 

Pitcher-plant, 23, 91 

Pitcher-plant Family, 91 

Planera albelica, 82 

Plantain, 38 

Plant body, 8, 9, 11 

Plant communities, 76 

Plant Kingdom (Plantae), 41, 

Bryophyta, 41, 63 

Anthocerotae (Hornworts), 63 

Hepaticae (Liverworts), 63 

Musci (Mosses), 63 

Charophyta (Stoneworts), 41, 62 

Chlorophyta (Green Algae), 41, 58 

Cycadophyta (Cycads), 41, 71 

Equisetophyta (Horsetails & Scouring 

Rushes), 41, 66 

Ginkgophyta, 41, 72 

Gnetophyta (Gnetes), 41, 74 

Lycopodiophyta, 41, 65 

Isoetales (Quillworts), 65 

Lycopodiales (Clubmosses), 65 

Selaginellales (Spikemosses), 65 

Magnoliophyta (Flowering Plants), 41, 

75 

Liliopsida (monocotyledons), 75 

Magnoliopsida (dicotyledons), 75 

Phaeophyta (Brown Algae), 41, 59, 60, 

61

Ectocarpales, 59 

Fucales, 61 

Laminariales (kelps), 60 

Pinophyta (Conifers), 41, 73 

Polypodiophyta (Ferns), 41, 67 

Marsileales (water ferns), 70 

Ophioglossales (adder’s-tongue 

ferns), 67 

Polypodiales (common ferns), 68, 69 

Salviniales (floating ferns), 70 

Psilophyta (Whisk Ferns), 41, 64 

Rhodophyta (Red Algae), 41, 57 

Bangiophycidae, 57 

Florideophycidae, 57 

Plantago, 38 

Plasmolysis, 5 

Plasmopara viticola, 46 

Platycerium, 67 

Pleurotus, 50 

Plum, 99 

Poa, 123 

Poaceae (Grass Family), 10, 15, 19, 22, 

23, 24, 35, 38, 76, 122, 123, 125 

Podosphaera, 48 

Poinciana, 100 

Poinsettia, 23, 26, 103 

Poison-ivy, 106 

Poison-oak, 106 

Poison-sumac, 106 

Poison-wood, 106 

Pollen (pollen grain), 27, 30, 31, 33, 34, 

35, 36, 37, 71, 72, 73, 74, 75, 92, 

94, 97, 108, 111, 112, 113, 115, 

118, 119, 120, 124, 127, 129, 130 

Pollen sac, see Stamen structure 

Pollen tube, 31, 37 

Pollination, 33, 34, 35, 36, 37 

cross-pollination, 33, 92, 109, 113 

self-pollination, 33, 92, 109, 125 

wind pollination, 33, 35, 75, 82, 83, 84, 

88, 89, 95, 105, 123, 125 

Pollinators 

bats, 36 

birds, 36, 116 

insects, 33, 34, 35, 75, 81, 92, 95, 109, 

113, 125, 127, 129, 130 

bees, 34, 110, 113, 115, 129 

beetles, 33 

butterflies, 33 

flies, 34, 127 

moths, 33, 34, 117 

Polygamodioecious condition, 28, 102 

Polygamomonoecious condition, 28 

Polygonaceae, 89 

Polygonatum, 128 

Polygonum, 89 

Polyploidy, 6 

Polypodiophyta, 41, 67, 68, 69, 70 

Polyporus, 50 

Polysiphonia, 57 

Poncirus, 107 

Pond spice, 78 

Poplar, 35, 95 

Poppy, 38 

Poppy mallow, 90 

Populus, 95 

Porana paniculata, 112 

Porcupine sedge, 122 

Porphyra, 57 

Potato, 3, 16, 46, 111 

Pothos, 127 

Prayer plant, 124 

Precatory bean, 100 

Prickly ash, 107 

Prickly-pear, 85 

Privet, 114 

Protein (amino acids), 2, 3, 6, 24, 34, 36, 

37, 40, 43, 123 

Prunus, 39, 99 

Pseudotsuga, 73 

Psilocybe, 50 

Psilophyta, 41, 64 

Psilotum, 43, 64 

Ptelea, 107 

Pteridium, 67 

Pterocephalus, 118 

Puccinia, 49 

Pueraria lobata, 100 

Puffball, 53 

Pumpkin, 94 

Pyracantha, 99 

Pyrethrum, 119 

Pyrola, 97 

Pyrrophyta, 41, 55 

Pyrus, 99 

Pythium debaryanum, 46 

Pyxie cup, 54 

Quaking aspen, 95 

Quamoclit pennata, 112 

Queen Anne’s lace, 109 

Queen-of-the-border, 90 

Queen palm, 125 

Quercus, 38, 83 

Quillworts, 41, 42, 65 

Quince, 8, 99 

Radish, 96 

Raffia, 125 

Ragweed, 119 

Ragwort, 119 

Ramonda, 116 

Ranunculaceae, 80 

Ranunculus, 80 

Raphanus, 96 

Raphia, 125 

Rasamala, 81 

Raspberry, 99 

Rechsteineria, 116 

Red Algae, 4, 41, 57 

Red campion, 87 

Red crown cactus, 85 

Red-hot-poker, 128 

Redleg, 89 

Red-osier dogwood, 101 

Red squill, 128 

Redwood, 15, 73 

Reindeer moss, 54 

Reproduction 

asexual: 

budding, 47 

division (fission), 3, 7, 43, 44, 47, 55, 

56 

fragmentation, 47, 56, 57, 59, 63 

asexual structures: 

akinete, 44 

bulb, 8, 12, 16, 18, 128, 129 

conidium, 47, 48 

corm, 12, 16, 18, 65, 128, 129 

cyst, 55, 58 

gemma, 63, 64 

isidium, 54 

pseudobulb, 16, 130 

pycnidium, 54 

rhizome, 16, 20, 65, 66, 67, 68, 70, 

79, 92, 108, 124, 128, 129 

sporangium (spore case), 46, 59, 60, 

64, 65, 66, 67, 68 

sporocarp, 70 

stolon, 16, 20 

strobilus, 65, 66 

tuber, 3, 8, 16, 18, 112, 130 

tuberous root, 18 

sexual: 

anisogamy, 55, 59 

isogamy, 55, 59 

oogamy, 56, 57, 59, 60, 61, 62 

sexual structures: 

aethalium, 45 

antheridium, 46, 56, 60, 61, 62, 63, 

64, 66, 67 

archegonium, 63, 64, 66, 67 

ascus, 47, 48 

basidium, 49, 50, 51, 52, 53 

carpogonium, 57 

gametangium, 46, 59 

megasporangium, 32, 65 

microsporangium, 31, 65, 71 

oogonium, 46, 56, 60, 61, 62 

plasmodiocarp, 45 

sporangium (spore case), 45, 46, 47, 

49, 71, 72, 74 

strobilus, 71, 72, 73, 74 

trichoblast, 57 

Resin, 2, 10, 15, 22, 98, 106 

Respiration, 3, 24, 43 

Rex begonia, 93 

Rhapidophyllum, 125 

Rhapis, 125 

Rheum, 89 

Rhizine, 54 

Rhizobium radicicola, 43 

Rhizoid, 57, 58, 62, 63, 64 

Rhizome, 16, 20, 65, 66, 67, 68, 70, 79, 

92, 108, 124, 128, 129 

Rhizophora, 12 

Rhizophore, 65 

Rhizopus, 47 

Rhododendron, 38, 97 

Rhodophyta, 41, 57 

Rhoeo, 121 

Rhubarb, 89 

Rhubarb chard, 88 

Rhus, 106 

Rhynia, 43 

Ribes, 98 

Rice, 3, 19, 26, 38, 44, 70, 123 

Ricinus communis, 103 

Rinorea, 92 

River-bank grape, 104 

RNA (ribonucleic acid), 2, 3, 24 

Rock cress, 96 

Robinia, 38, 100 

Roccella, 54 

143

Rocket, 96 

Root, external structure, 12, 13, 17, 20, 

40 

coleorhiza, 40 

nodule, 12, 43, 100 

root cap, 3, 9, 13, 20 

root hair, 9, 10, 13, 17 

root tip (apex), 9, 13, 25, 40 

Root types, 12 

adventitious roots, 12, 13, 16, 123, 129 

aerial roots, 12, 20 

contractile roots, 12 

lateral root, 12, 13, 20 

primary root, 12 

prop roots, 12 

radicle, 12, 40 

seminal roots, 12 

storage roots, 12, 18 

tap root, 12, 109 

tuberous roots, 18 

Rosa, 99 

Rosaceae (Rose Family), 39, 99 

Rose, 99 

Rose cactus, 85 

Rose Family, 39, 99 

Rosemary, 113 

Rose-of-China, 29, 90 

Rose-of-Sharon, 26, 90 

Roselle, 90 

Rosidae, 75 

Rosmarinus, 113 

Royal fern, 67, 68 

Royal palm, 125 

Royal water lily, 79 

Roystonea regia, 125 

Rubus, 39, 99 

Rubutia, 85 

Rudbeckia hirta, 26, 119 

Rue anemone, 80 

Rumex crispus, 38 

Rumohra adiantiformis, 69 

Rush Family, 35 

Russelia, 115 

Russula, 51 

Rusty hoof fungus, 52 

Ruta, 107 

Rutabaga, 96 

Rutaceae (Rue Family), 39, 107 

Rye, 19, 48, 123 

Ryegrass, 26 

Sabal palmetto, 125, 126 

Sacaline, 89 

Saccharomyces, 47 

Saccharum, 123 

Saffron, 129 

Sage, 113 

Sagittaria latifolia, 120 

Sago palm, 125 

Saguaro cactus, 36 

Saint Augustine grass, 123 

Saintpaulia ionantha, 116 

Salicaceae (Willow Family), 35, 95 

Salix (willow), 10, 35, 95 

Salvia, 113 

Salvinia, 70 

Sambucus, 117 

Sandwort, 87 

144 

Sansevieria, 20, 128 

Sap, 2, 8, 18, 79, 89, 103, 110, 112, 127 

Saponaria, 87 

Saprolegnia, 46 

Saprophyte, 46, 49, 115, 130 

Sarracenia, 23, 91 

Sarraceniaceae, 91 

Sassafras albidum, 78 

Satureja, 113 

Saucer magnolia, 77 

Savory, 113 

Saw-palmetto, 125 

Saxifraga, 16, 98 

Saxifragaceae, 98 

Saxifrage Family, 98 

Scabiosa, 118 

Scarlet oak, 83 

Scarlet sage, 113 

Scenedesmus, 58 

Scent (odor, aroma, fragrance), 33, 34, 

35, 36, 62, 72, 78, 98, 109, 111, 

113, 127, 130 

Schinopsis, 106 

Schizanthus, 111 

Scirpus, 122 

Schlumbergera, 26, 85 

Scilla, 128 

Scindapsis, 127 

Scotch elm, 82 

Scleranthus, 87 

Sclerotium, 45, 48 

Scouring rush, 20, 41, 42, 66 

Script lichen, 54 

Scrophularia, 115 

Scrophulariaceae, 115 

Sea grape, 89 

Sea holly, 109 

Secale cereale (rye), 19, 48, 123 

Sedge, 122 

Sedge Family, 23, 76, 122 

Seed, 27, 37, 38, 39, 40, 41, 71, 72, 73, 

74, 77, 79, 81, 82, 84, 86, 87, 90, 

92, 93, 95, 96, 99, 100, 102, 105, 

106, 107, 108, 110, 111, 128, 129, 

130 

Seed ferns, 41, 42 

Seedling, 20, 40 

Seed structure, 37, 40 

aleurone, 40, 123 

coleoptile, 20, 40 

coleorhiza, 40 

coma (surface hairs), 10, 90, 95 

embryo, 12, 37, 40, 75, 107, 123 

endosperm, 8, 37, 40, 75, 123, 125, 

130 

epicotyl, 40 

hilum, 40 

plumule, 40 

radicle, 12, 40 

seed coat (testa), 20, 37, 40, 123 

seed leaf (cotyledon), 1, 8, 37, 40, 72, 

75 

scutellum, 40 

Seed types 

angiosperm, 41, 75 

dicot, 40, 75 

monocot, 40, 75 

gymnosperm, 41, 71, 72, 74 

conifer, 40, 41, 71, 73 

cycad, 41, 71 

Ginkgo, 41, 71, 72 

gnete, 41, 71, 74 

Selaginella, 65 

Semibegoniella, 94 

Senecio, 119 

Senna, 100 

Sensitive fern, 67 

Sensitive plant, 100 

Sentinel palm, 125 

Sentry palm, 125 

Sequoiadendron giganteum, 73 

Sequoia sempervirens, 73 

Serenoa, 125 

Setaria, 123 

Shaggy mane, 51 

Shallot, 128 

Sheepberry, 117 

Shepherd’s purse, 96 

Shinleaf, 97 

Shoot, 9, 19, 20, 37, 40 

bud, 14, 19, 25, 29 

plumule, 40 

spur shoot, 16, 72, 99 

tiller, 19 

tip (apex), 14, 15, 16, 18 

Siberian elm, 82 

Sidalcea, 90 

Silica, 2, 10, 56, 66 

Silver-lace vine, 89 

Silver maple, 14, 38, 105 

Silver palm, 125 

Silvery lupine, 100 

Sinningia, 116 

Sisyrinchium, 129 

Skunk cabbage, 34, 127 

Slime molds, 41, 45 

Slipper-flower, 115 

Smartweed, 89 

Smilacina, 128 

Smilax, 16, 128 

Smithiantha, 116 

Smoke tree, 106 

Snake plant, 128 

Snapdragon, 115 

Sneezeweed, 119 

Snowberry, 117 

Solanaceae, 111 

Solanum 

dulcamara, 111 

nigrum, 111 

pseudocapsicum, 111 

tuberosum (potato), 3, 16, 111 

Solidago, 38, 119 

Solomon’s seal, 128 

Sonchus, 119 

Sorbus, 99 

Sorghum bicolor, 24, 123 

Sorus, 67, 68 

South African stinkwood, 78 

Sow-thistle, 119 

Soybean, 100 

Spadix, 34, 75, 127 

Spathe, 34, 75, 127 

Spathiphyllum, 127 

Spatterdock, 79 

Spiraea, 99

Speedwell, 115 

Sperm, 31, 37, 56, 59, 60, 61, 62, 63, 64, 

66, 67, 71 

Sphaerotheca, 48 

Sphagnum, 63 

Spice bush, 78 

Spiderwort, 121 

Spiderwort Family, 121 

Spikemosses, 41, 42, 65 

Spinach, 26, 88 

Spinacia oleracea, 26, 88 

Spinulose woodfern, 68 

Spirillum lipoferum, 43 

Spirogyra, 58 

Spore, 45, 46, 47, 48, 49, 50, 53, 54, 57, 

63, 65, 66, 67 

ascospore, 47, 48, 54 

basidiospore, 49, 50, 51, 53, 54 

carpospore, 57 

conidium, 47, 48 

endospore, 43 

exospore, 44 

megaspore, 27, 32, 65, 70 

microspore, 31, 65, 70, 71 

oospore, 46, 56, 62 

statospore, 56 

teleutospore, 49 

tetraspore, 57 

zoospore, 46, 56, 59, 60 

zygospore, 47 

Sporophyte, 40, 59, 60, 63, 64, 66, 67 

Spruce, 73, 76 

Spurge Family, 16, 103 

Squash, 94 

Squill, 128 

Staff-tree Family, 102 

Stagger-bush, 97 

Stagger-grass, 128 

Staghorn fern, 67 

Staghorn sumac, 106 

Stamen structure, 27, 28, 30, 31, 33, 35, 

36, 75, 77–130 

androecial types: 

didynamous, 115 

monadelphous, 90 

tetradynamous, 96 

anther (pollen sac), 27, 29, 30, 31, 33, 

35, 77, 78, 79, 81, 82, 90, 93, 94, 

97, 106, 108, 110, 111, 112, 113, 

114, 116, 119, 120, 121, 123, 124, 

127, 128, 129 

connective, 27, 93, 113 

filament, 27, 29, 31, 35, 36, 79, 87, 90, 

94, 96, 97, 100, 104, 106, 107, 

108, 111, 112, 113, 119, 120, 121, 

127, 128, 129 

pollen, see Pollen 

staminode, 78, 116, 121, 124 

tapetum, 31 

Stanhopea, 130 

Stapelia, 110 

Star anise, 77 

Starch, 3, 13, 24, 36, 37, 39, 40, 55, 57 

Star magnolia, 77 

Star-of-Bethlehem, 128 

Starwort, 87 

Stellaria, 87 

Stem, external structure, 14, 15, 40 

areole, 85, 86 

bud scale scar, 14 

internode, 14, 15, 16, 25, 62, 66 

leaf scar, 14, 35, 71, 83 

lenticel, 14, 15, 17 

node, 14, 16, 21, 62, 66, 74, 85, 87, 

89, 100, 104 

spur shoot, 16, 77, 99 

vascular bundle scar, 14 

Stemonitis, 45 

Stem types 

bulb, 8, 13, 16, 18, 128, 129 

conifer, 9, 15 

corm, 12, 16, 18, 65, 128, 129 

dicot, 9, 15 

herbaceous stem, 1, 9, 15, 65 

monocot, 9, 15 

pedicel, 27, 35, 39, 78, 95, 96, 100, 

102, 103, 104, 106, 107, 108, 109, 

110, 111, 113, 114, 115, 116, 120, 

121 

peduncle, 26, 27, 29, 33, 34, 36, 39, 

79, 80, 81, 91, 92, 98, 99, 101, 

103, 107, 108, 109, 110, 112, 115, 

117, 119, 120, 121, 124, 127, 128, 

129, 130 

pseudobulb, 16, 130 

rhizome, 16, 20, 65, 66, 67, 68, 70, 79, 

92, 108, 124, 128, 129 

stolon, 16, 20 

storage stem, 16 

succulent (fleshy) stem, 16, 17, 85, 93, 

103 

tuber, 3, 8, 16, 18, 112, 128, 130 

vine, 12, 16, 20, 67, 74, 78, 80, 89, 94, 

97, 102, 104, 106, 111, 113, 114, 

116, 117, 119 

woody stem, 1, 9, 15, 72, 73 

Stenotaphrum, 123 

Stephanotis floribunda, 110 

Stinkhorns, 53 

Stock, 96 

Stomata, 10, 15, 17, 22, 23 

Stoneworts, 41, 62 

Stork’s-bill, 108 

Strawberry, 20, 26, 39, 99 

Strawberry-blite, 88 

Strawberry begonia, 16, 98 

Strawflower, 119 

Strelitziaceae, 124 

Streptocarpus, 116 

String-of-hearts, 110 

Striped inch plant, 121 

Strobilus, 65, 66, 71, 72, 73, 74 

Stroma, 3, 24, 48 

Stylites, 65 

Succulent plants, 17, 23, 67, 76, 93, 103, 

110, 128 

Sugar, 2, 5, 10, 18, 24, 33, 37 

Sugar beet, 88 

Sugar cane, 24, 123 

Sugar maple, 26, 105 

Sugar palm, 125 

Suillus, 51 

Sulfur mushroom, 50 

Sumac, 106 

Sundew, 23 

Sunflower, 19, 119 

Swamp laurel, 97 

Swamp mallow, 90 

Sweet alyssum, 96 

Sweet-bay, 77 

Sweet bay, 78 

Sweet cicely, 109 

Sweet clover, 100 

Sweet gum, 81 

Sweet orange, 107 

Sweet pea, 100 

Sweet potato, 12, 112 

Swiss chard, 88 

Swiss-cheese plant, 127 

Sycamore maple, 105 

Symbegonia, 93 

Symphoricarpos, 117 

Symplocarpus foetidus, 34, 127 

Synchytrium, 46 

Synechococcus, 44 

Syringa vulgaris, 14, 114 

Tagetes patula, 75, 119 

Tahitian bridal veil, 121 

Talauma, 77 

Tamarack, 73 

Tamarind, 100 

Tamarindus, 100 

Tangerine, 107 

Tannia, 127 

Tannin, 10, 15, 22 

Tan oak, 83 

Taphrina, 47 

Tapioca, 103 

Taraxacum, 119 

Taro, 127 

Tarragon, 119 

Taxodium, 73 

Taxus, 73 

Teasel, 118 

Teasel Family, 118 

Temple bells, 116 

Tendril, 16, 94, 100, 104 

Tetradymia, 119 

Tetragonia expansa, 88 

Tetraphis, 63 

Thanksgiving cactus, 26, 85 

Thalia dealbata, 124 

Thalictrum, 80 

Thistle, 119 

Thlaspi, 96 

Thrinax, 125 

Thuja, 73 

Thyme, 113 

Thymus, 113 

Tilletia, 49 

Timothy, 123 

Tissue 

dermal tissue, 9, 13 

collenchyma, 15, 39 

cortex, 8, 9, 13, 15, 17, 72 

endodermis, 9, 13, 17, 22 

endosperm, 8, 37, 40, 75, 123, 125, 

130 

epidermis, 8, 9, 10, 13, 15, 22, 23, 24, 

39 

ground tissue, 9, 13, 15, 22 

hypodermis, 22 

leaf tissue, 17, 22 

145

mesophyll, 15, 17, 22, 23, 24 

parenchyma, 8, 13, 15, 16, 18, 22, 38, 

39, 56 

pericycle, 9, 13, 17 

periderm (outer bark), 9, 15, 102 

phelloderm, 9, 15 

pith, 8, 9, 15, 72, 122 

root tissue, 13 

sclerenchyma, 8, 13, 15, 22, 38 

stem tissue, 15 

transfusion tissue, 22 

vascular tissue, 2, 8, 9, 11, 13, 15, 17, 

18, 22, 37, 42, 63 

phloem (food-conducting), 8, 9, 11, 

13, 15, 17, 18, 22, 24, 42 

xylem (water-conducting), 2, 8, 9, 

11, 13, 15, 17, 18, 22, 24, 42 

Tmesipteris, 43, 64 

Tobacco, 34, 111 

Tomato, 3, 4, 111 

Toothed fungus, 52 

Torch lily, 128 

Torenia, 115 

Toxicodendron, 106 

Trachycarpus fortunei, 125 

Trachymeme, 109 

Tradescantia, 121 

Translocation, 18 

Transpiration, 10, 17 

Trebouxia, 54 

Tree fern, 67 

Tree-mallow, 90 

Tremella, 49 

Trifoliate orange, 107 

Trifolium, 12, 26, 33, 100 

Trillium, 128 

Tripterygium, 102 

Triticum (wheat), 19, 49, 123 

aestivum, 26 

Tropisms, 20 

Truffle, 48 

Tsuga, 73 

Tuber, 3, 8, 16, 18, 112, 128, 130 

Tuber, 48 

Tuberous begonia, 12, 93 

Tulip, 128 

Tulipa, 128 

Tulip tree, 77 

Turgor pressure, 5, 10, 123 

Turkey tail fungus, 52 

Twinflower, 117 

Typhaceae (Cattail Family), 35 

Ulmaceae (Elm Family), 35, 82 

Ulmus, 38, 82 

Umbellularia californica, 78 

Umbrella plant, 122 

Umbrella sedge, 122 

Umbrella tree, 77 

Urginea, 128 

146 

Urocystis cepulae, 49 

Urophlyctis, 46 

Usneas, 54 

Ustilago, 49 

Utricularia, 23 

Uvularia, 128 

Vaccinium, 97 

Vanda, 130 

Vanilla, 130 

Varnish tree, 106 

Vascular bundle (vein), 8, 9, 11, 14, 15, 

22, 23, 24, 25, 99 

Vaucheria, 56 

Velvet-leaf, 90 

Vein, see Vascular bundle 

Venus’-flytrap, 23 

Veratrum, 128 

Verbascum thapsus, 115 

Vernal witch hazel, 81 

Veronica, 115 

Verpa,48 

Vetch, 100 

Viburnum, 117 

Vicia, 100 

Victoria amazonica, 79 

Viola, 23, 92 

Violaceae, 92 

Violet, 23, 92 

Violet Family, 92 

Virginia creeper, 16, 104 

Vitaceae, 104 

Vitamin, 24, 92, 123 

Vitis (grape), 16, 39, 104 

Vivipary, 107 

Voodoo lily, 127 

Wafer ash, 107 

Walking fern, 67 

Walnut bean, 78 

Wandering Jew, 121 

Wapato, 120 

Washingtonia filifera, 125 

Water canna, 124 

Water clover, 70 

Water cress, 96 

Water fern, 44, 70 

Water hemlock, 109 

Water lettuce, 127 

Water lily, 79 

Water Lily Family, 79 

Watermelon, 94 

Water-plantain, 120 

Water-plantain Family, 120 

Water shield, 79 

Water spangles, 70 

Wattle, 100 

Wax begonia, 93 

Wax-plant, 110 

Wayfaring tree, 117 

Weigela, 117 

Welwitschia, 15, 74 

West Indian arrowroot, 124 

West Indian silkwood, 107 

Wheat, 19, 26, 49, 123 

Whisk ferns, 41, 64 

White birch, 84 

White campion, 87 

White snakeroot, 119 

Wild black currant, 98 

Wild buckwheat, 89 

Wild cabbage, 96 

Wild calla, 127 

Wild carrot, 38, 109 

Wild mustard, 96 

Williamsonia, 42 

Willow, 10, 35, 95 

Willow Family, 35, 95 

Wind flower, 80 

Winged wahoo, 102 

Wintergreen, 97 

Winter hazel, 81 

Wishbone flower, 115 

Wisteria, 100 

Witch hazel, 81 

Witch Hazel Family, 81 

Wolffia, 75 

Wood, 1, 9, 14, 15, 72, 73, 75 

Wood rose, 16, 112 

Xanthium strumarium, 26, 119 

Xanthoria, 54 

Xanthosoma, 127 

Xylaria, 48 

Xylem, 2, 8, 9, 11, 13, 15, 17, 18, 22, 24, 

42 

Yeast, 47 

Yellow-green Algae, 41, 56 

Yellow poplar, 77 

Yellow water lily, 79 

Yew, 73 

Yucca, 15 

Yulan magnolia, 77 

Zamia furfurscea, 71 

Zantedeschia, 127 

Zanthoxylum, 107 

Zea mays (corn), 12, 19, 24, 40, 123 

Zebrina pendula, 121 

Zingiberaceae, 124 

Zingiberales, 124 

Zingiberidae, 75 

Zinnia, 119 

Zoysia, 123 

Zoysia grass, 123 

Zygadenus, 128 

Zygomycota, 41, 47 

Zygote, 37, 45, 46, 60, 62, 63, 64, 66, 

67

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