Japan Flora: Rhi­zomes long; culms loosely tufted, about 60 cm. long; leaf­blades rather firm, 2-3 mm. wide, the lower leaf-sheaths bladeless, brownish; spikes 3 to 5, the upper ones continuous, the terminal staminate, 2-4 cm. long, the lateral pistillate, short-cylindric, 1.5-4 cm. long, erect, sessile, the lowest bract leaflike, about as long as the inflorescence; pistillate scales oblong, obtuse, dark brown, with white margins, 3-nerved; perigynia slightly longer than the scales, 2 mm. long, pale green, planoconvex, nerveless, nearly beakless, with entire mouth; stigmas 2. May-June. Wet river banks in low­lands.

Honshu (Tohoku and Kanto Distr.); rare. Korea.