Japan Flora: Rhizomes clustered, long-creeping; culms rather stout, 40-100 cm. long; leaf-blades 4-8 mm. wide, flat, rather stiff, the basal sheaths partially dark reddish purple, splitting into fibers, the terminal staminate, linear-cylindric, 4-7 cm. long, dark reddish purple, the others pistillate, cylindric, sessile or peduncled, erect or nodding, densely many-flowered, 3-10 cm. long, the bracts leaflike, sheathless; pistillate scales ovate to oblong, sometimes cuspidate, purple-brown; perigynia longer than the scales, 3-4 mm. long, spreading to divergent, glabrous, thick-membra­nous, inconspicuously nerved or nerveless except for 2 costal nerves, greenish, dark brown when dried, dull, the beak long, recurved, with an obliquely truncate hyaline tip; stigmas 3, rather thick, deciduous.  Apr.-July. Wet places around ponds and along rivers in lowlands; Hokkaido, Honshu, Shi­koku, Kyushu; common.  Korea, Ussuri, Manchuria, China, s. Kuriles, and Sakhalin.

var. takeuchii (Ohwi) Ohwi.  Culms 30-70 cm. long; leaf-blades softer, the basal sheaths pale; peri­gynia thinner, light yellowish, slightly brownish when dried, closely investing the achene, the beak slightly elongate, erect; stigmas 3, slender, persistent, longer than the perigynium. May-June. Wet places along streams and ravines in mountains; Honshu (Kinki, Chugoku Distr.)