The "Ao-mizu" (Pilea mongolica) belongs to Urticaceae (the Nettle family). It is an annual herb that is native all over Japan, as well as Taiwan, the Korean Peninsula, China and the eastern Siberia. This herb grows in moist grasslands and can reach 30-50 cm in height. The leaves are ovate, three-veined and coarsely serrate. They have also long petioles and are arranged oppositely. The slender female and male flowers bloom in the axils from July to October. The tender leaves and stems are used as a wild vegetable. It is difined by the about 10 serrated edges on one side of leaf blade and the petiolated inflorescences. It is called "短角冷水麻" in Taiwanese Chinese and "透茎冷水花" (tou jing leng shui hua) in Chinese.