Tree-skirt moss

IUCN Red List

LC - Least Concern

NatureServe

NNR - Unranked
SNR - Unranked

Minnesota

not listed

Tree-skirt Moss is a common, large, feather moss. It occurs in Europe, eastern Asia, North America, and Central America. It occurs in the United States and southern Canada east of the Great Plains, with a few scattered populations in the west. It is common in Minnesota. It is found in forests, brushy meadows (meadow/carrs), swamps, bogs, peatlands, and river shores. It most often grows as a large, dense, rough mat on the base of hardwood trees, but smaller populations are found on wet cliffs, bedrock outcrops, rocky shores, and mineral-rich soil. In rocky areas it is found on or associated with limestone, sandstone, or dolomite.

The stems are light green to light yellowish brown, leafy, ⅝″ to 1¼″ (15 to 30 mm) long, and 1⁄32″ (0.8 to 1.0 mm) thick. Older primary stems usually lay flat on the ground or against the substrate. When on a tree trunk or other vertical surface, younger stems grow out from the base and droop slightly. When on the ground they are sprawling to ascending. Primary stems are blunt at the tip. Young stems are often attenuate, and this is the feature that gives the plant its species epithet “attenuatus.” Attenuate branches are tapered gradually to a very slender, thread-like or needle-like tip. The leaves are much smaller and thinner, and they are tightly wrapped around the stem. This makes the branch look like a thin green string. Some attenuate branches eventually fill out with normal-sized leaves. Some can become significantly longer and whip-like, essentially “runners,” that can start a new colony where they touch the ground.

The branch leaves are closely spaced, spirally arranged, and overlapping. When wet, the top and bottom leaves are twisted sharply at the base to point out toward the sides, and the lateral leaves stay spreading outward. They end up lying on the same horizontal plane, making the branch appear flattened. When dry, the leaves curl inward and become tightly appressed to the stem, making the branch appear cylindrical, like a string or a rat tail.

Branch leaves are 3⁄64″ to 3⁄32″ (1.2 to 2.2 mm) in length. The blade is slightly narrowed in the middle. The leaf base is broadly attached and runs down the stem (decurrent). The tip is usually narrowly angled (acute), sometimes broadly angled (obtuse). The margins are flat and usually entire (untoothed), but there are very small teeth near the tip. The midrib (costa) is strong. It extends beyond the midpoint and in most interior leaves it ends near the tip.

The sporophyte (the spore-producing generation) is rarely produced. When present, it consists of a smooth, cylindrical capsule elevated on a long stalk (seta). The seta is slender and ⅜″ to ⅝″ (10 to 15 mm) long. The capsule is 1⁄16″ to ⅛″ (1.6 to 2.8 mm) long. At the end of the capsule there is an obliquely angled opening. When immature, the capsule opening (mouth) is covered with a membranous hood (operculum) and a large, cap (calyptra). The operculum has a short extension (beak) at the tip. At maturity, the calyptra splits and falls away revealing a double ring of minute teeth, which regulates the release of spores. The teeth on the outer ring (exostome) are irregular and 1⁄64″ (0.3 mm) long. The basal membrane on the inner ring (endostome) is 3 or 4 cells high.

Growth Form

Pleurocarp

Height

Similar Species

Forests, brushy meadows (meadow/carrs), swamps, bogs, peatlands, and river shores

Phenology

Capsules mature in early to mid-fall.