"Naruko-suge" (Carex curvicollis) belongs to the Cyperaceae (the Sedge family). It is a perennial herb that is distributed throughout Japan. This grass grows along mountain streams, and it can reach 20-40 cm in height. It spreads by short runners and forms large clumps. The leaves are narrow linear with flat or moderate M-shaped cross-section. The acrogyrous spikes are male, linear and 1-2 cm long, and the 2-6 pleurogerous spikes are female, 1.5-4 cm long with drooping tips.