Plant morphology　 an annual herb, 20-80cm high, the whole plant has a fragrance. The stems are erect, often in clusters, and sparsely hairy. Three compound leaves alternate; lobules are long ovate or ovate-lanceolate, 1-3.5cm long, 0.5-1.5cm wide, sparsely pilose on both sides; petiole is long, stipule and petiole are connected. Flowers sessile, 1-2 axillary; calyx tube-shaped; corolla butterfly-shaped, white, gradually light yellow, slightly purple at the base; stamens 10, disomy; ovary linear, slender pod, flat cylindrical, slightly Curved, 6-11cm long, 0.5cm wide, with reticulate veins and pilose, long beak at the tip. The seeds are 10-20, brown and fragrant. Flowering period from April to June, fruiting period from July to August.

Many cultivation. Mainly produced in Anhui, Sichuan and Henan.

When the fruit is mature, the whole grass is cut, the seeds are laid, and the seeds are dried. For raw or slightly stir-fried use.

"Character" The seeds are slightly oblique, with a length of 3-5mm, a width of 2-3mm, and a thickness of about 2mm. The surface is yellowish-brown or reddish-brown, with slightly gray short hairs, and there is a deep oblique groove on each side, and the navel is the place where the two grooves meet. Hard quality. Fragrant, slightly bitter taste.