The Amur corktree (Phellodendron amurense) belongs to Rutaceae (the Citrus family). It is a tall deciduous tree that is distributed to all over Japan, Sakhalin, the southern Kuril Islands, the Korean Peninsula and China. This tree grows in mountains and can reach 10-25 m in height. The barks have thick cork layer and bright yellow inner barks. The leaves are imparipinnate with narrow-ovate leaflets. It is dioecious. The small yellow flowers come in May to June. The fruits are globose, ripen black and remain until winter. The yellow inner barks are used as digestive medicine or dye, and the fruits are also used as anthelminthic. It is called "黄檗" (huang bo) in Chinese.