HUMULUS, in botany, a genus of the diœcia pentandra class. The calix of the male is divided into five parts, and it has no corolla. The calix of the female consists of one entire leaf opening at one side; the corolla is wanting; it has two styli; and the nut has two valves, and is inclosed within the calix. There is but one species, viz. the lupulus, or hop, a native of Britain. See HOP.