"Tani-tade" (Circaea erubescens) belongs to Onagraceae (the Evening primrose family). It is a perennial herb that is distributed to all over Japan, Taiwan, China and southern Sakhalin. This herb grows in mountane wet places and can reach 20-50 cm in height. The stems and leaves are tinged reddish. The leaves are long-ovate and arranged in opposte with wavy serrate edges. The racemes are borne on the stem apices and the white to pale rose pink, small flowers bloom in July to September. The corolla consists of two petals, two calyx lobes and two stamens. The fruits are egg-ball-shaped nuts and covered with dense hooked hairs.