A genus of medium to large mosses, in which the archegonia (and hence capsules) are borne terminally on short, lateral branches. Stems are erect or prostrate, often with numerous short branches. It is a cosmopolitan genus, with about 80 species. Most are saxicolous, mainly on acidic rocks. R. aciculare grows on acidic rocks near or in water. R. aquaticum grows mainly on wet acidic rocks and on ledges in mountainous regions, often near flowing water. R. lanuginosum grows on exposed mountain tops on rock or on peat, often forming extensive mats and giving its name to the plant community of this habitat: Racomitrium heath (formerly Rhacomitrium heath). In this species each leaf has a long hair point (often as long as the leaf itself), which is rough with minute teeth; the plant has a characteristic grey-green colour, and the shoots appear hoary because of the massed, white hair points.
Subjects: Plant Sciences and Forestry.