barley, in botany, a genus of the triandra digynia class. The involucrem consists of six leaves, and contains three flowers. There are eight species, only one of which, viz. the morimum, or wall-barley-grass, is a native of Britain. The native place of the vulgare, or common barley cultivated in our fields, is not known. For the culture, &c. of common barley, see Agriculture, p. 61.