Dried rhizome of Dioscorea villosa L., Dioscoreaceae. Habit. North America. Constit. Saponin, acrid resin. Account of the nature, origins, cultivation and utilization of the useful members of the Dioscoreaceae: D. G. Coursey, Yams (London, Longmans, 1967) 230 pp. See also Yam, Mexican.