Polytrichum

a genus of plants of the class Musci. Of the approximately 100 species, more than ten are found in the USSR, in the mountains, forests, swamps, and tundra. The most common species is Polytrichum commune, which is distributed in marshy taiga evergreen forests. They grow in large pulvinate clumps of turf. The stem, which is densely covered with leaves that have assimilative lamellae on their upper sides, reaches a height of 40 cm. The plant produces an abundance of spores. The capsule containing the spores is located on a long stalk that is structurally different from the stalks of other representatives of the class Musci. The top of the capsule is covered with calyptera, which have downwardly directed pili (resembling flax yarn) and easily fall off. This plant’s turf-like growth and its leaf structure cause a surface accumulation of moisture and lead to the formation of marshes.