Yam is a dry tuber of Dioscorea zingiberensis, a perennial herbaceous plant in the Dioscoreaceae family. Planters are called home yam , wild ones are called wild yam; Chinese medicinal materials are called yam, yam, yam, etc. Because of its rich nutrition, it has been regarded as a good and cheap tonic product since ancient times. It can be used as staple food, vegetable, and snacks such as candied haws . Our country is mainly produced in Bo’ai, Qinyang, Wuzhi, Wenxian and other places in Henan Province. It is also cultivated in Hebei, Shanxi, Shandong, Central South and Southwest. After the stems and leaves are withered in winter, excavate, cut off the roots, wash and dry. The yam cultivated in China mainly includes ordinary yam and field potato. Common yam has small tubers. Among them, the “foot potato” in Sichuan and other places, Huai yam in Huai County, Shanxi, and Huai yam in Jianghan Nancheng are the most famous.