Tongcai is a sweet potato genus light calyx group of annual herbaceous plants, native to East Asia, is now widely cultivated as a vegetable, but also part of the wild growth, not hardy, accustomed to grow in the climate of the warm and humid, fertile and humid soil, widely distributed in the south-central part of China's Fujian, Guangxi, Guizhou, Jiangsu, Sichuan, Guangdong Province, and other provinces, and the north is relatively less.

Tongcai distribution in the world is spread throughout tropical Asia, Africa and Oceania, can be used as medicine and food, but also a better feed.