The "Yama-guwa" (Morus bombycis) belongs to Moraceae (the Mulberry family). It is a semi-tall deciduous tree that is distributed widely from Japan to Taiwan, the Korean Peninsula, China and the Himalaya. This leaves have been used as a feed for silkworms before Asuka Era (538-710). It is monoecious or dioecious. The flowering clusters are borne on the axiles from April to May. The flowers are non-petaled. The fruits are aggregate and ripen in red to black from June to July. The Japanese name "kuwa" is a corruption of "kuba" (edible leaf) or "koba" (silkworm's leaf), which is the food of silkworms. In Taiwanese Chinese, it is called "小桑樹", and in Chinese, "鶏桑" (ji sang).