Dioscorea villosa

Yam Yam (y[a^]m), n. [Pg. inhame, probably from some native name.] 1. (Bot.) A large, esculent, farinaceous tuber of various climbing plants of the genus {Dioscorea}; also, the plants themselves. Mostly natives of warm climates. The plants have netted-veined, petioled leaves, and pods with three broad wings. The commonest species is {Dioscorea sativa}, but several others are cultivated. [1913 Webster]

2. (Bot.) Any one of several cultural varieties of the sweet potato. [U. S.] [Webster 1913 Suppl.]

{Chinese yam}, a plant ({Dioscorea Batatas}) with a long and slender tuber, hardier than most of the other species.

{Wild yam}. (a) A common plant ({Dioscorea villosa}) of the Eastern United States, having a hard and knotty rootstock. (b) An orchidaceous plant ({Gastrodia sesamoides}) of Australia and Tasmania. [1913 Webster]