moss

noun

A cryptogamous plant of a cellular structure, with distinct stem and simple leaves. The fruit is a small capsule usually opening by an apical lid, and so discharging the spores. There are many species, collectively termed Musci, growing on the earth, on rocks, and trunks of trees, etc., and a few in running water. The term moss is also popularly applied to many other small cryptogamic plants, particularly lichens, species of which are called tree moss, rock moss, coral moss, etc. Fir moss and club moss are of the genus Lycopodium.