yam bean a name applied to several leguminous plants with swollen edible tubers. The most important is Pachyrhizus erosus, a perennial vine native to C. and S. America which has in the last few hundred years been introduced to most tropical and subtropical regions of the world, including parts of Africa, India, SE Asia, and Hawaii (where it is said to bear the name ‘chopsui potato’).

The tuber is starchy with a crisp texture and a slightly sweet taste. It can be eaten raw; or cooked, e.g. in soups; or sliced and made into chips. The Chinese include it with stir-fried vegetables as an alternative to water chestnuts or bamboo shoots. They also pickle it. In Indonesia the tuber is used in making rujak, a sharp and spicy salad in which fruits are the main ingredients.