Asian tick trefoil (Desmodium heterocarpon) belongs to the Fabaceae (the Pea family). It is a perennial herb that is distributed from Shizuoka Prefecture of Honshu west to Shikoku and Kyushu, as well as Taiwan, China, Southeast Asia, Australia and the Pacific Islands. This herb grows in grasslands and forests, and up to a height of 30-150 cm. The leaves are trifoliate with elliptic to broard obovate leaflets. The purple or white, papilionacenous flowers bloom in the apical or axillary racemes from July to October. The fruits are loments with 5-8 quadrangular mericarps.