The Ussurian water-milfoil (Myriophyllum ussuriense) belongs to the family Haloragaceae. It is a perenniak herb that is distributed not only in various parts of Japan, but also in the Korean Peninsula, China, Ussuri, and Amur. Some of these plants grow in water and some grow in wetlands. In water it can be 50 cm long, and in wetlands the stems can stand upright and grow to 6-20 cm. It is dioecious and blooms small pale yellowish white flowers on the upper axils from June to August.