Description from Flora of China
Stems emersed, erect, robust, 70-120 cm tall or more. Leaves (20-)40-90 cm × 7-16 mm, upper flattened, lower keeled or trigonous on abaxial side. Panicles (8-)20-60 cm, with 3-7 lateral branches, each with (1 or)7-11 male heads and 1 or 2 female heads; main axis consisting of 3-5 or more male heads. Male flowers: perianth segments spatulate, lobate at apex; filaments ca. 3 mm; anthers obconic, (0.5-)1-1.2 × ca. 0.5 mm. Female flowers: perianth segments 5-7 × 1-1.5 mm; ovary sessile; styles forked or simple, ca. 1.5 mm; stigmas 3-4 mm. Fruit obconic, (3.5-)6-9 mm, ribbed. Fl. and fr. May-Oct.
Lakes, ponds, swamps, streams; below 3600 m. ?Anhui, Gansu, Hebei, Heilongjiang, ?Henan, Hubei, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Shaanxi, ?Shandong, Shanxi, Xinjiang, Xizang, Yunnan, ?Zhejiang [Afghanistan, Japan, Kazakhstan, Korea, Mongolia, Pakistan, Russia, Tajikistan, Uzbekistan; SW Asia, North America].