Mniaceae. Genus Trachycystis

1. Leaf margins distinctly bordered by two rows of linear cells, with geminate teeth; plants usually with numerous flagellae 1. T. flagellaris

This species has a classical Beringian distribution: Alaska in North America and Japan, China, and Korea in Asia. In the Russian Far East it is very common in the Pacific Islands, Kamchatka and in the southern part of the Far East mainland. It grows abundantly on the bases of tree trunks, rotten logs and stumps. When flagellae are present the species is immediately recognizable because no other similar regional species has flagellae. When flagellae are absent T. flagellaris can be recognized by the presence of arcuate shoots with complanate, rigid, intensely yellowish-green leaves. This intense yellowish-green color is often associated with mammillose or papillose leaf cells.

Leaf margins unbordered or indistinctly bordered, with simple teeth; plants without flagellae 2

2. Leaves strongly incurved to contorted when dry; leaf margins indistinctly bordered by one or two rows of large, pellucid cells; leaf cells mamillose and papillose 2. T. microphylla

This East Asian species is known in the Russian Far ast from only a few localities in north temperate mixed forests. It grows on cliffs. The presence of strongly curved leaves and much smaller plants than those of T. ussuriensis are helpful in recognizing it in the field.

Leaves appressed to slightly flexuose when dry; leaf margins unbordered; leaf cells smooth or slightly bulging 3. T. ussuriensis

Trachycystis ussuriensis is common in the southern part of the Russian Far East and southern Siberia. It occurs disjunctly more to the north in Central Yakutia and Chukotka. It is also known from the Caucasus, where itis a rare species. Grows on rock outcrops and soil, occasionally forming continuous carpets on river gravel bars. The strongly curved, tumid shoots of T. ussuriensis resemble those of Thamnobryum species, but plants of Thamnobryum are strongly branched, while sterile shoots of Trachycystis are mostly unbranched.