a genus of bog, or peat, mosses (Sphagnales). Of the 320 species, 42 are found in the USSR. The genus consists predominantly of mosses that grow in dense aggregates, forming large cushions or unbroken carpets on sphagnum bogs. The plants are less commonly found in rain forests. The soft, erect stem is 10–20 cm tall; the branches are arranged in clusters. Both the stem and the single-layer leaves contain a large number of dead water-bearing cells, whose pores readily absorb water. This accounts for the high moisture capacity of sphagnum mosses and promotes rapid development of upriver swamps in places where the mosses appear. The lower stems die off annually and form peat; the apical branches, however, continue to grow. Sphagnum mosses are distributed predominantly in the tundra and forest zones of the northern hemisphere; in the southern hemisphere they are found high in the mountains or, less commonly, in the plains of the temperate zone.