The "Tsuta-urushi" (Rhus ambigua) belongs to Anacardiaceae (the Sumac family). It is a deciduous woody vine that is native all over Japan, the Kuril Islands, Sakhalin and the Korean Peninsula. This vine grows in montane beech forests and climbs up adjacent trees by the aerial roots. The leaves are tri-lobed compound and turn red in fall. The panicles are borne in the axils and the yellowish-green flowers bloom from May to June. It is dioecious. Careless touching can cause skin rash.