Chinese yam
Dioscorea polystachya or Chinese yam (Chinese: 山药), also called cinnamon-vine, is a species of flowering plant in the yam family. It is sometimes called Chinese potato or by its Japanese name nagaimo.
It is a perennial climbing vine, native to China and East Asia. The edible tubers are cultivated largely in Asia and sometimes used in alternative medicine. This species of yam is unique as the tubers can be eaten raw.

source