vine ( Pachyrhizus erosus , or P. tuberosus ), also called yam bean.
A legume native of Mexico and Central and South America, it is grown for its edible root. The irregularly globular, brown-skinned tubers are white-fleshed, crisp, and juicy. There are two varieties, those with clear juice and those with milky juice. Both have a mild flavour and are eaten raw or cooked. Sometimes very young seedpods of the plant are eaten, but the mature seeds are highly toxic.