Vigna subterranea (L.) Verdc.

An annual plant. It can either form a bunchy bush or be a trailing plant. Often the creeping stems are near ground level. It often appears as if bunched leaves arise from branched stems near ground level. It has a well developed taproot. The leaves have 3 leaflets. The leaf stalk is erect and thickened near the base. The end leaflet is slightly larger than the side leaflets. Leaflets are about 6 cm long by 3 cm across. The flowers are yellowish-white. They occur in pairs. The fruit are pods which are round and with one seed. Some kinds have 3 seeds. This pod develops under the ground on a long stalk. The flower/fruit stalk elongates after being fertilised and pushes into the soil. The seeds are hard and are of many colours. Pods can be 3.7 cm long.

It is a tropical plant. It can grow in hot climates. It can also grown on poor soils. It does best with moderate rainfall and sunshine. It can tolerate drought. Long day-lengths can reduce or prevent pod development in some kinds. It suits semi-arid regions. In Kenya it grows from sea level to 1,550 m altitude. It can grow in arid places.

Seeds can be eaten fresh or roasted while immature. Mature seeds are hard so must be boiled before being used in cooking. Pre-soaking seeds and cooking with potash makes cooking easier. Young pods are cooked and used as a vegetable. They are used in stews. Seeds can be dried and made into flour and used for baking. They can be popped like corn. The seeds are roasted as a coffee substitute. The leaves can be eaten.

Plants are grown from seed. Plants are often put in rows 50 cm apart and with 15 cm spacing between plants. Ridges are formed to enable the pods to penetrate the soil. It is mostly grown intercropped with other plants. Soil should be light and friable and the seed bed loose and fine. Normally the whole plant is pulled up for harvesting. Any pods which become detached are harvested by hand. Pods are dried in the air before threshing.