The seeds are slightly flat, disc-shaped, slightly convex in the middle, about 2 ~ 3 cm in diameter and about 5 mm thick. The surface is grayish brown or grayish black, rough, with concave reticular patterns, and there are more than a dozen opposite serrated protrusions on both sides of the periphery.

The outer seed coat is hard and brittle, the inner seed coat is film-like, the surface is gray-green and fluffy, and there are two large and fat cotyledons in it, which are yellow and white, rich in oil, with a special greasy taste and bitter taste.

It is best to have full, unbroken seeds with heavy weight, yellow and white seeds and no oil stains.

Location: Guangxi, Sichuan and Hubei.

In addition, it is also produced in Hunan, Guizhou, Yunnan, Guangdong and Anhui.