The Families of Angiosperms

L. Watson and M.J. Dallwitz

Epacridaceae R. Br.

~ Ericaceae-Styphelioideae.

Including Prionotidaceae (Prionotaceae) Hutch., Stypheliaceae Horan.; excluding Wittsteinia.

Habit and leaf form. Small trees, or shrubs (often ‘ericoid’); leptocaul, or pachycaul. Helophytic to xerophytic (mostly on acid substrates). Leaves persistent; minute to medium-sized; alternate (usually), or whorled (at least, with distant very tight spirals in Leucopogon verticillatus); spiral (usually), or four-ranked; flat, or rolled; ‘herbaceous’, or leathery; imbricate, or not imbricate; petiolate to sessile; sheathing (Cosmelia, Andersonia, Sprengelia, Dracophyllum, Richea Sphenotoma — in the first three, associated with a very peculiar mode of leaf abscission, resulting in sloughing away of the outer parts of the stem), or non-sheathing. Leaf sheaths when present, with free margins. Leaves simple; epulvinate. Lamina entire; one-veined, or palmately veined (commonly), or parallel-veined (genuinely so in Richeoideae, but only ostensibly so in Cosmelieae where the parallel veins in the lamina originate palmately from a single leaf trace); cross-venulate, or without cross-venules. Leaves exstipulate. Lamina margins flat, or revolute.

Leaf anatomy. The leaf lamina dorsiventral. Stomata mainly confined to one surface (then usually abaxial, but sometimes adaxial only in Leucopogon), or on both surfaces (commonly so in Andersonia and Dracophyllum); anomocytic (most Epacridoïdeae), or paracytic (Richeoïdeae), or cyclocytic (some Epacridoideae-Cosmelieae). Hairs absent, or present (but then inconspicuous, infrequent, and uniform, by contrast with the diversity exhibited by the Ericaceae); if present,exclusively eglandular; unicellular. Unicellular hairs simple. Complex hairs absent. Adaxial hypodermis present, or absent. Lamina without secretory cavities. The mesophyll containing crystals. The crystals druses and solitary-prismatic. Midrib usually not conspicuous. Main veins vertically transcurrent, or embedded. Minor leaf veins without phloem transfer cells (Leucopogon).

Axial (stem, wood) anatomy. Secretory cavities absent. Cork cambium present to absent (in that a distinct phellogen is not always clearly defined); initially deep-seated. Nodes unilacunar (mostly), or tri-lacunar to multilacunar (Dracophyllum, Richea). Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow, or mixed wide and narrow.

The wood diffuse porous. The vessel end-walls scalariform and simple, or simple. The vessels without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem with tracheids; with fibre tracheids (typically), or without fibre tracheids (?); with libriform fibres, or without libriform fibres; including septate fibres (rarely), or without septate fibres. The fibres with spiral thickening, or without spiral thickening. The parenchyma apotracheal (sometimes sparse). ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite (nearly always). Pollination entomophilous, or ornithophilous; mechanism conspicuously specialized (with Acrotriche serrulata exhibiting passive pollen presentation via corolla hairs), or unspecialized.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’. Inflorescences when flowers aggregated, terminal, or axillary. Flowers bracteate; bracteolate; small to medium-sized, or minute (rarely); fragrant, or odourless; regular; mostly (4–)5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present (usually), or absent (e.g. Sprengelia); intrastaminal; of separate members, or annular.

Perianth with distinct calyx and corolla; 8 (Oligarrhena), or 10; 2 whorled; isomerous. Calyx 4 (Oligarrhena only), or 5; 1 whorled; polysepalous; regular; persistent; imbricate. Corolla 4 (Oligarrhena only), or 5; 1 whorled; polypetalous, or gamopetalous. Corolla lobes markedly shorter than the tube to markedly longer than the tube. Corolla imbricate, or valvate (or induplicate-valvate in Needhamiella only), or contorted (Lysinema); regular; green, or white, or red, or pink, or purple, or blue, or yellow (rarely, but exemplified in the peculiar monotypic, Oligarrhena); persistent, or deciduous.

Androecium (4–)5, or 2 (Oligarrhena). Androecial members free of the perianth (Andersonia, Sprengelia, Lysinema, Prionotes, Lebetanthus), or adnate (to the corolla); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (4–)5 (usually), or 2 (Oligarrhena); inserted when epipetalous, midway down the corolla tube, or in the throat of the corolla tube; reduced in number relative to the adjacent perianth to isomerous with the perianth; oppositisepalous (hypogynous or epipetalous); alternating with the corolla members; laminar, or filantherous, or with sessile anthers. Filaments appendiculate (or auricled, in Andersonia auriculata), or not appendiculate. Anthers dorsifixed (usually), or basifixed (rarely), or apicifixed (ostensibly, when basifixed but inverted), or adnate (rarely, e.g. in Andersonia spp.); becoming inverted during development, their morphological bases ostensibly apical in the mature stamens (sometimes? - requiring investigation), or not becoming inverted during development (usually); non-versatile; dehiscing via short slits (rarely - e.g. Rupicola), or dehiscing via longitudinal slits (usually by a single median slit, but rarely by two — e.g. Conostephium); introrse; unilocular (usually), or bilocular; bisporangiate; unappendaged (but their apices sometimes sterile). Endothecium not developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. Tapetum glandular. Pollen shed in aggregates (usually), or shed as single grains; without viscin strands; when aggregated, in diads, or in triplets, or in tetrads (in Styphelioideae often shed as tetrads with 1–3 abortive members). Pollen grains aperturate; 3 aperturate, or 4–10 aperturate; porate (commonly), or colporate (commonly), or foraminate, or rugate; not lophate; 3-celled.

Gynoecium (2–)5(–10) carpelled (consistently 2 only in Oligarrhena and Needhamiella). The pistil (1–)5(–10) celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary (1–)5(–10) locular. Gynoecium stylate. Styles 1; attenuate from the ovary (Styphelieae, Oligarrhena, Needhamiella), or from a depression at the top of the ovary (Cosmelieae, Epacrideae, Richeoideae); apical (usually), or ‘gynobasic’ (Archeria). Stigmas 1; truncate, or clavate, or capitate. Placentation axile, or axile to apical (e.g. Leucopogon), or basal to axile (Archeria). Ovules 1–50 per locule (i.e. to ‘many’); pendulous (usually), or ascending (Archeria); non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; proliferating (e.g. in Leucopogon), or not proliferating. Synergids with filiform apparatus. Endosperm formation cellular. Endosperm haustoria present; chalazal and micropylar (usually, but the former rudimentary in Brachyloma), or micropylar (no chalazal haustorium in Styphelia). Embryogeny caryophyllad to solanad.

Fruit fleshy, or non-fleshy; dehiscent (Cosmelieae, Epacrideae, Richeoideae), or indehiscent (Styphelieae, Oligarrhena, Needhamiella); a capsule (when dehiscent), or a drupe. Capsules loculicidal. The drupes with separable pyrenes, or with one stone. Seeds endospermic. Endosperm oily. Seeds wingless. Embryo well differentiated. Cotyledons 2. Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C₃. Anatomy non-C₄ type (widely examined by L.W.). Cyanogenic, or not cyanogenic. Alkaloids present (rarely), or absent. Arbutin absent. Iridoids detected; ‘Route I’ type (normal). Saponins/sapogenins absent. Proanthocyanidins present; cyanidin, or cyanidin and delphinidin. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid absent (3 genera). Ursolic acid present. Aluminium accumulation not found.

Geography, cytology. Temperate to tropical. Indonesia to New Zealand, Hawaii to southern South America, but mainly Australia. X = 4–14.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Ericales. Cronquist’s Subclass Dilleniidae; Ericales. APG III core angiosperms; core eudicot; Superorder Asteranae. APG IV Order Ericales (as a subfamily of Ericaceae).

Species about 400. Genera about 35; Acrothamnus, Acrotriche, Andersonia, Androstoma, Archeria, Astroloma, Brachyloma, Choristemon, Coleanthera, Conostephium, Cosmelia, Cyathodes, Cyathopsis, Decatoca, Dracophyllum, Epacris, Lebetanthus, Leptecophylla, Leucopogon, Lissanthe, Lysinema, Melichrus, Monotoca, Needhamiella, Oligarrhena, Pentachondra, Planocarpa, Prionotes, Richea, Rupicola, Sphenotoma, Sprengelia, Styphelia, Trochocarpa, Woolsia.

General remarks. Submerged of late in the Ericaceae by pedantic nomenclatural interpretation of cladistic theories, this exclusively southern hemisphere assemblage differs from the traditional, sensu stricto version of that family almost absolutely in the tetracyclic flowers and non-versatile, bisporangiate stamens; the general glabrosity of “this, the most glabrous of families” (Étienne, 1919) stands in remarkable contrast to the spectacular range of hair types found in abundance in Ericaceae; particular states of 78 characters included in the present compilation (including very conspicuous vegetative, floral and pollen-morphological features) are either confined to or are very rare in the one family or the other; and arbutin, andromedotoxin and inulin seem not to have been found in Epacridaceae. For classificatory analyses, see Watson 1967; Watson, Williams and Lance 1967.

Quotations.

Squarrosely cushioning the rocks
About the King George Sound
(anon - of Andersonia sprengelioides)

Magnifications on the unscaled image: 1–8, X 475, 9–10, X 950. From Franks and Watson (1963). • Pollen: Astroloma, Brachyloma, Melichrus, Oligarrhena. 1, Astroloma ciliatum Druce (grain solitary); 2, Astroloma conostephioides F. Muell. ex Benth. (tetrad showing the one mature grain in optical section, and two of the three abortive grains); 3, A. conostephioides (a tetrad with two mature grains and two split aborted ones); 4, Brachyloma ericoides Sond. (surface view of a diad); 5, B. ericoides (optical section of the diad, showing the two aborted grains); 6, Brachyloma daphnioides Benth. (a solitary grain showing the tetrad scar); 7, Melichrus urceolatus R. Br. (grain solitary); 8, Oligarrhena micrantha R. Br. (grain solitary, minute, asymmetric).

Magnifications in the unscaled image: 1–7, X 475; 8, X 950. From Franks and Watson (1963). • Pollen: Acrotriche, Cyathodes, Pollen: Cyathopsis, Lissanthe, Monotoca, Pentachondra. 1, Cyathopsis floribunda Brong. et Gris. (complete tetrad); 2, Lissanthe strigosa R. Br. (complete tetrad); 3, Cyathodes pumila Hook. f. (tetrad with two aborted grains); 4 and 5, Cyathodes straminea R. Br. (complete tetrads); 6, Decatoca spenceri F. Muell. (complete tetrad); 7, Pentachondra pumila R. Br. (complete tetrad); 8, Trochocarpa gunnii Benth. (complete tetrad); 9 and 10, Pentachondra verticillata Hook. f. (tetrad with three aborted grains); 11 and 12, Acrotriche divaricata R. Br. (two tetrads, with one and 3 aborted grains, respectively); 13 and 14, Monotoca scoparia R. Br. (tetrad with 3 aborted grains).

Magnifications in the unscaled image: 1–7 and 11–12, X 475; 8–10 and 13–14, X 950. From Franks and Watson (1963). • Pollen: Leucopogon (8 species), Needhamiella. 1 and 2, Leucopogon tenuis DC. (ostensibly solitary grain with aborted members of the tetrad represented by wall thickenings); 3, Leucopogon malayanum Jack. (abortive members of the tetrad detectable only in optical section of the ostensibly solitary grain); Leucopogon richei R. Br. (ostensibly solitary grain, with aborted grains represented by the thickened wall); 5, Leucopogon cordifolius Lindl. (solitary grain); 6, Leucopogon conostephioides DC. (solitary grain); 7, Leucopogon ericoides R. Br. (solitary grain); 8 and 9, Needhamiella pumilio (R. Br.) L. Watson (tetrad with only one aborted member); 10 and 11, Leucopogon fasciculatus A. Rich. (ostensibly solitary pollen, with aborted members visible in optical section); 12, Leucopogon ericoides R. Br. (solitary grain).

Magnifications in the unscaled image: 1–4 and 6–12, X 950; 5, X 475. From Franks and Watson (1963).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 25th April 2024. delta-intkey.com’.

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