Species name: Dioscorea Scientific name: Dioscorea opposita Alias: Chinese yam, Huaiyam, Huaiyam, potato, yam, potato, Yuyan. Odor: (root) sweet, warm, flat, non-toxic. Distribution of origin: Distributed in various provinces and regions in North my country, Northwest China and the Yangtze River Basin. Cultivators call it domestic yam, and wild people call it wild yam; Chinese medicinal materials are called yam, yam, yam, etc. Because of its rich nutrition, it has been regarded as a high-quality and low-cost tonic since ancient times. It can be used as a staple food, a vegetable, and can also be made into snacks such as candied haws. Our country is mainly produced in Boai, Qinyang, Wuzhi, Wenxian and other places in Henan Province. It is also cultivated in Hebei, Shanxi, Shandong, central and southwestern regions and other regions. In winter, excavate after the stems and leaves have withered, cut off the roots, wash and dry. There are two main types of yams cultivated in China: ordinary yam and field potato. Ordinary yam tubers are smaller, among which the "foot potato" from Sichuan and other places, the Huaiyam from Huai County, Shanxi, and the Nancheng Huaiyam from Jianghan are the most famous. Therapeutic effects of yam: yam is sweet in taste and neutral in nature, enters the lung, spleen, and kidney meridian; it is not dry or greasy; it has the functions of strengthening the spleen and lungs, benefiting the stomach and kidneys, strengthening the kidneys and essence, improving ears and eyesight, supporting the five internal organs, strengthening muscles and bones, and improving ambition. It has the effect of calming the mind and prolonging life; it is mainly used to treat weak spleen and stomach, fatigue and weakness, loss of appetite, chronic ejaculation and dysentery, lung qi deficiency and dryness, phlegm and cough, kidney qi deficiency, soreness and weakness of the waist and knees, weakness of the lower limbs, thirst and frequent urination, spermatorrhea and premature ejaculation, and vaginal discharge. Symptoms such as white turbidity, red and swollen skin, and obesity. They are sold in many agricultural and sideline markets. They are long and often used in soups in Guangdong. They are delicious.