HORDEUM, BARLEY, in botany, a genus of the triandria digynia class. The involucre consists of six 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, no 118, — 122.