Yam and yam are the same. As a medicine, we should use yam. I bought it from a drugstore. Because it is processed, the effect is better than fresh. There are two kinds of folk names, yam and yam. They think there is no difference between the two, but they are not. Huaiyan refers to the yam produced in Jiangsu, Anhui and other places today, and Huaiyan refers to the yam produced in Jiaozuo, Henan today. The best in Jiaozuo are wen county, Qinyang, Wuzhi and Aibo. No matter from the medicinal value or nutritional value, yam medicine can not be compared with yam. Shennong's materia medica contains: "Huai Mountain in Henan is good." Yam is very easy to cook, usually it can be cooked completely in seven minutes, but the cooking time of ordinary yam (also called vegetable yam) is much longer, often taking twenty or thirty minutes. Therefore, local people (Huaiqing people) usually bring a pot to perform live when selling yam. Only real yam can be cooked seven times.