Sweet potato, commonly known as horny potato, is twined with vines; Most of the wild tubers are cylindrical or rod-shaped, and the cultivated shape changes greatly, such as palm, rod or cone, with brown or black surface and white, yellow or purple cross section. It has the effect of cooling down the fire and is ideal for making soup. In addition, there is steamed meat with sweet potatoes. There are many sweet potatoes in Hainan, which are cheap, about one kilogram of 2 yuan. It is a kind of health food for strengthening the stomach. Sweet potato, also known as root tuber yam in Sichuan, has similar stomach-invigorating effect and similar taste.