Easy to identify, fern mosses look like tiny ferns. Just like many fern fronds, the branches are on a single plane, are longer at the base, and become shorter toward the tips. The branches are 3-times pinnate (3-times feather compound), just as in many ferns. Instead of sticking straight up or lying flat, these mosses lean over at an angle — again, like fern fronds. The color of fern mosses varies from golden brown to bright spring green.
Fern mosses are pleurocarpous (carpet-forming, branching) mosses that can cover rotten logs, boulders, or patches of damp soil. They also often appear mixed in among other types of mosses.
The leaves are very small; they are so tiny, they are not helpful in field identifications, even with a hand lens. Even tinier than the leaves, the mosses in this group also have interesting, often branching filaments called paraphyllia scattered on the stems; with a hand lens, these make the moss look fuzzy. To the naked eye, the combination of tiny leaves, paraphyllia, and tiny wartlike bumps (papillae) give fern mosses a finely bumpy appearance.
The sporophytes in this group are not commonly seen. When present, they are stalked, pointy-tipped, oblong or cylindrical capsules that are slightly curved and inclined, giving the overall shape of a cormorant’s, duck’s, or flamingo’s head.
Missouri has approximately 3 species of fern mosses in genus Thuidium. Thuidium delicatulum, the common fern moss or delicate fern moss, is one very common species.
It is difficult for amateurs to distinguish between the species of fern mosses. Botanists use microscopes to examine the tiny leaves, paraphyllia, and cells for exact identifications.
Learn more about Missouri’s mosses on their group page.
Similar species: As with many other mosses, fern mosses have been grouped together or divided over the years within their family; Missouri has 7 species in 3 genera in the fern moss family.
Length: frond-like stems to about 1 inch; colonies may cover large patches of soil, rock, or rotting logs.
Statewide.
Habitat and Conservation
Common in moist, shady places, on soil, rotting logs, rocks, and among other mosses. Sometimes they form large colonies.
Fern mosses, along with tree mosses (Climacium spp.), are among the dominant plants in Missouri’s forested fen natural communities.
Life Cycle
As with other mosses, fern mosses have alternating generations. The plant we usually think of as the moss is the gametophyte generation (it’s a gamete-, or sex-cell-bearing plant). In separate organs, it produces sperm and eggs. When water, even a thin layer of rainwater, is present, the sperm can swim to the eggs and fertilization occurs. The resulting offspring plant, called a sporophyte (spore-bearing plant), grows out of the female organs of the gametophyte. In fern mosses, the sporophyte takes the form of a stalked capsule growing out of small side branches of the gametophyte stem. It obtains nutrients from the gametophyte. When mature, the capsule opens to release spores, which can grow into new gametophyte plants.
Mosses also commonly reproduce asexually when a portion of the plant breaks away, gets moved elsewhere, and continues growing as a separate plant.
Human Connections
Fern mosses are simply cute. They reward us when we bother to stop for a few minutes and look closely at the miniature world all around us. We are fortunate to live in a world of wonders!
The genus name, Thuidium, is derived from Thuja, the genus name for the evergreen shrub known as arborvitae or northern white cedar — a common landscaping shrub with remarkably flattened branches and compressed scale-like leaves. The scientist who bestowed fern mosses’ genus name apparently thought their branching stems resembled the foliage of arborvitae.
Ecosystem Connections
Mosses and other small, low plants form a microhabitat where many types of insects and other invertebrates live. Earthworms, centipedes, sowbugs, springtails, snails, and a wide variety of other small animals live in and around mosses. Tartigrades, or water bears, are curious microscopic eight-legged animals that often live among mosses. Shrews, salamanders, frogs, tiny snakes, and other insectivores hunt for a variety of small animals among the mosses.
Fern mosses and tree mosses (Climacium) are some of the mosses preferred by female four-toed salamanders for nesting sites along small, fishless creeks. Thick mats of these mosses overhanging the water are ideal for this species, whose females remain with the eggs for about four weeks, until just before hatching time.
Many kinds of birds, as well as mice and other mammals, use moss in nest building. They rely on its ability to cushion fragile eggs and delicate, naked young; to insulate against cool weather; and to camouflage the nest, concealing it from predators. Even bumblebees use mosses in their nests.
Because many mosses are able to grow on rock or on open ground, they are important in preventing soil erosion and in building soil, allowing larger plants to move into previously uninhabitable areas.
Mosses, liverworts, hornworts, and lichens seem rather similar, but these organisms are in very different groups. Mosses, liverworts, and hornworts are small, low plants usually found in damp habitats. Unlike more familiar plants, they lack veinlike structures and do not produce flowers or seeds — instead, they produce spores. Meanwhile, lichens are not plants at all: they are a collection of different fungi that have photosynthetic algae living within their tissues.