R. amoemum (previously Sematophyllum amoenum) is probably the most common species. In the field, this species is difficult to differentiate from smaller forms of Hypnum cupressiforme and also other similar looking members of the Sematophyllaceae. Microscopic examination is almost always needed to ascertain the identity of this species.

R. amoemum grows in small clumps over rock, rotting wood and sometimes on bark. The leaves have a distinct alar region, with moderately thick-walled alar cells. The cells of the capsule walls have thickenings in the corners.

The other species, R. calliferum, may be a variety of the preceding species.