water-moss, in botany: A genus of the natural order of musci, belonging to the cryptogamia class of plants. The anthera is hooded; the calyptra, or covering of the anthera, fleshy, inclosed in a perichaetium or empalement of leaflets different from those of the rest of the plant. There are four species, all of them natives of Britain. They grow on the brinks of rivulets, and on the trunks of trees. The most remarkable is the antipyretica, with purple stalks. The Scandinavians line the insides of their chimneys with this moss, to defend them against the fire; for, contrary to the nature of all other moss, this is scarcely capable of burning.