Japan Flora: Stems 50-100 cm. long, erect, 3-10 mm. across, green, simple or with irregular whorls of branches in the middle, smooth, slenderly 10- to 30-grooved, the central cavity 4/5 the diameter of the stem; sheaths 5-12 mm. long, green, tight, the teeth 15-20, small, subulate-lanceolate, acuminate, blackish, scarcely or narrowly scarious on margin; branches ascending, slender, simple, 5- angled, the sheaths green, the teeth 4 or 5, subulate, green, ascending and acuminate; spikes 1-2 cm. long, pedunculate or subsessile. Fruiting May-July. Boggy places;

Hokkaido, Honshu (centr. and n. distr.). s. Kuriles, Sakhalin, Korea, Siberia to Europe, and N. America.