The "Aze-suge" (Carex thunbergii) belongs to Cyperaceae (the Sedge family). It is a perennial herb that is native to Hokkaido and Honshu in Japan. This herb grows on rice field linches, stream banks or around bogs, and can reach 20-80 cm in height. It speads under ground by stolons and often forms clumps. The leaves are linear and tinged powdery white on abaxial sides. The 3-5 spikes are borne on the tip of flowering stalks from April to June. The 1-2 acrogyrous spikes are male and the pleurogerous spikes are female.