the yam family of the flowering plant order Dioscoreales, consisting of 4 genera and 870 species of herbaceous or woody vines and shrubs, distributed throughout tropical and warm temperate regions. Members of the family have thick, sometimes woody roots or tuber-like underground stems and net-veined, often heart-shaped leaves that sometimes are lobed. The small green or white flowers of most species are borne in clusters in the leaf axils. The fruit is a winged capsule or a berry. Several species of yams (yam) (vines of the genus Dioscorea) are grown for their edible tuberous roots, such as Chinese yam, or cinnamon vine (D. batatas); air potato (D. bulbifera); and yampee, or cush-cush (D. trifida).

A few species are cultivated as ornamentals. Black bryony (Tamus communis) is a European perennial vine with yellow flowers, poisonous red berries, and poisonous blackish root tubers. Dioscorea is a principal raw material used in the manufacture of birth-control pills.