"Komiyama-mizu" (Pilea pseudopetiolaris) belongs to Urticaceae (the Nettle family). It is an annual herb that is distributed from Kinki region of Honshu westward to Kyushu in Japan. It grows in moist, shady mountainous areas and is 40 to 50 cm tall. The leaves are 8-15 cm long, oblong, with three conspicuous veins and sharp serrations on the edges. The leaves are similar to those of "Miyama-mizu" (Pilea petiolaris), but the tips of the leaves grow long and caudate. It is dioecious, with male and female inflorescences in the leaf axils from July to October, and produces pale green, inconspicuous flowers. The achene is very small, about 0.5 mm.