Andreaea

Andreaea is a genus of mosses commonly called rock mosses, first described by the German botanist Johann Hedwig in 1801. Its species are small, delicate mosses that form dark brown or reddish cushions on wet siliceous rocks in mountainous areas, with the moss capsules formed at the tips of vertical branches. The capsule lacks the peristome teeth and lid found in most other mosses, instead opening by splitting along four vertical slits whose valves stay joined at the base and the tip. The capsule has no seta of the usual moss kind; instead the sporophyte is held up by a pseudopodium built from the plants own gametophyte tissue, a structure the genus shares with Sphagnum, and its spores germinate into thalloid protonemata.