Sheng Di Huang

Sheng Di Huang (生地黄) is the fresh or dried unprocessed root tuber of Rehmannia glutinosa (Gaertn.) DC., a perennial herb in the Orobanchaceae (formerly Scrophulariaceae) native to northern and central China. The plant reaches 10–30 cm tall, with a basal rosette of obovate, crinkled, soft-hairy leaves and erect stems bearing tubular, two-lipped flowers in dull reddish-purple with yellow throats. The fleshy, fusiform root tubers are pale yellow-orange when fresh and turn dark brown to nearly black on drying. Sheng Di Huang denotes the unprocessed form, distinguished from Shu Di Huang (the wine-steamed, blackened root); the unprocessed root is cooling and moistening, while the processed form is warming and tonifying.