Description from Flora of China
Nemocharis radicans (Schkuhr) Beurling; Scirpus sylvaticus Linnaeus var. radicans (Schkuhr) Willdenow; Seidlia radicans (Schkuhr) Opiz.
Rhizomes short. Culms slightly tufted, 0.7-1.5 m tall, obtusely 3-angled, 7- or 8-nodose, smooth but slightly scabrous near inflorescence. Leaves cauline, shorter than inflorescence; sheath ± long; leaf blade 7-10 mm wide, abaxial midvein and margin slightly scabrous. Involucral bracts 2 or 3, leaflike, overtopping inflorescence. Inflorescence a terminal large compound anthela, with many rays; first rays to 9 cm, glabrous. Spikelets solitary, oblong-ovoid to narrowly ovoid, 5-8 × ca. 2 mm, many flowered, apex acuminate. Glumes densely arranged, oblong, ca. 2 mm, membranous, both surfaces dark grayish black, midvein pale yellow, base sometimes straw-colored, margin apically ciliate, apex rounded. Perianth bristles 6, usually 2-4 × as long as nutlet, prominently flexuose, retrorsely scabrous only near apex. Anthers ca. 1 mm, linear-oblong. Style slightly short; stigmas 3. Nutlet pale yellow, obovoid, ca. 1 mm, compressed 3-sided. Fl. and fr. Jun-Sep. 2n = 56.
In water, swampy places; 400-900 m. Heilongjiang, Jilin, Liaoning, Nei Mongol [Japan, Kazakhstan, Korea, Mongolia, Russia; Europe].