Stems 1.5-3 m tall, stout. Leaves 52-120 cm × 4-9 mm, abaxially convex, transverse section semicircular. Male part of spikes ca. 8 cm, with 1-3 deciduous bracts; female part of spikes (5-)15-30 cm, separated from male part by an axis 2.5-7 cm. Male flowers: stamens 3, rarely 2 or 4; anthers ca. 2 mm. Female flowers with bracteoles; bracteoles filiform; ovary fusiform; stalk ca. 5 mm, slender; styles 1-1.5 mm; stigmas linear to lanceolate, 1.3-1.8 mm; hairs on stalk shorter than style. Fruit narrowly elliptic. Fl. and fr. Jun-Sep. 2n = 30.

Shallow water of lakes, ponds, and rivers. ?Anhui, ?Fujian, Gansu, Guizhou, ?Hainan, Hebei, Heilongjiang, Henan, Hubei, Jiangsu, Jilin, Liaoning, Nei Mongol, ?Qinghai, Shaanxi, Shandong, Taiwan, Xinjiang, Yunnan, ?Zhejiang [?Afghanistan, India, Indonesia, Japan, Kazakhstan, Kyrgyzstan, Malaysia, Mongolia, Myanmar, Nepal, Pakistan, Philippines, Russia, Tajikistan, Thailand, Uzbekistan; SW Asia, Australia, Europe, North America].