Rhizoma Dioscoreae (Shan Yao, Chinese Yam) Rhizoma Dioscoreae (Shan Yao or Chinese Yam). The Rhizome of the perennial herbaceous trailing plant Dioscorea Opposita Thunb. of the family Diosoreaceae. Weight: 4 oz. This information has not been evaluated by the Food and Drug Administration...