Cowpea (Latin name: Vigna unguiculata (Linn.) Walp, alias: carob) is an annual plant of Leguminosae. It originated in tropical Africa and is widely cultivated in China.

There are three kinds of stems: dwarf, semi-tendril and tendril. The lobule 3, the terminal lobule rhomboid, 5 ~13cm long and 4 ~ 7cm wide, has a sharp tip, a nearly round or wide wedge-shaped base and no hair on both sides.

Lateral leaflets are obliquely ovate, stipules are ovate, about 1 cm long, with a short distance extending downward from the insertion site and a bell-shaped calyx; The corolla is pale purple, and there are pale yellow hairs in the upper part of the style. The pod is linear and can reach 40 cm long. The flowering and fruiting period is from June to September. Cowpea is a dry land plant and grows in fertile soil with deep and loose soil layer and strong fertilizer and water retention.

Annual twining, grassy vines or nearly erect herbs, sometimes with twining tips. Stems subglabrous. The pinnate compound leaves have 3 leaflets, the stipules are lanceolate, about 1 cm long, and the insertion place extends downward into a short distance with linear lines; Leaflets are ovate-rhombic, 5- 15 cm long and 4-6 cm wide, with acute apex and entire or nearly entire edges, sometimes lavender and glabrous.