1, yam should refer to the yam produced in Anhui, Jiangsu and other places today, while yam refers to the yam produced in Jiaozuo, Henan. The best in Jiaozuo are wen county, Qinyang, Wuzhi and Boai.

2. Chinese yam can't be compared with Chinese yam in terms of medicinal value and nutritional value. "Shennong Herbal Classic" contains: "Henan yam is good." Yam is very easy to cook, usually it takes seven minutes to cook completely, but ordinary yam (also known as vegetable yam) takes much longer to cook, often taking twenty or thirty minutes.

Therefore, when local people (Huaiqing people) sell yam, they usually bring a pot to perform on the spot. Only real yam can be cooked seven times.