It is an annual herb with a stout main root and fibrous lateral roots. The stem is slender, purplish-green, 12-32 cm tall, tetragonal, and sparsely hairy. Leaves vary from pinnate compound below to simple above, with serrate margins.
The flowers are purple or purplish-red, with a corolla tube extending slightly beyond the calyx, lips 3-lobed with the middle lobe inverted-heart shaped and side lobes ovate-triangular.
紫色
It is found in Hubei, Sichuan, Shaanxi, Hunan, Guangxi, and Yunnan provinces in China, growing under forests, along roadsides, and on grassy slopes at elevations of 700-2000 meters.