Japan Flora: Rhizomes elongate; culms 40-60 cm. long; leaf-blades flat, soft, 4-8 mm. wide, the basal sheaths pale, partially reddish purple; spikes 4 or 5, the upper 1 or 2 staminate, linear, 2-4 cm. long, the others pistillate, oblong, 2-3 cm. long, rather densely flowered, erect, distant, sessile, the lower peduncled, the lower bracts leaflike, scarcely sheathing; pistillate scales lanceolate-ovate, cuspidate, pale to stramineous; perigynia nearly twice as long as the scales, 10-12 mm. long, obliquely spreading, oblong-ovoid, inflated, thick but rather soft, light green but becoming dark grayish brown when dried, glabrous, ribbed, long-beaked, with a hyaline 2-toothed tip; stigmas 3. May-Jnne. Wet muddy places along rivers and ditches in lowlands.

Honshu (Kanto Distr. and westw.)5 Shi­koku, Kynshu. China.