Any of various leguminosae perennial herbs, having erect or oblique stem with much hair, 3( rarely 4) compound leaves. The leaf is ovate with crescent shape stripe on its surface. The plant has capitulum and pink and purple flowers. The anthesis is from May to June and the plant is harvested from June to July. The plant is originally native to Europe, West Asia and it widely grows all over the world at present. It is distributed in moderate zone and in China, it grows all over the country in the state of being wild or planted. It is mainly distributed in Northeast, Hunan, Jiangsu, Anhui, Zhejiang, Jiangxi, Guizhou, Yunnan provinces of China.