barley, in botany: A genus of the dycynia order, belonging to the triandra clas of plants; and in the natural method ranking under the 4th order, Gramina. The calyx is lateral, bivalved, uniflorous, and triple. The involucrum consists of five leaves, and contains three flowers. There are eight species; only one of which, viz. the murinum, 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. 139—146.