Aquatic perennial; culms submerged, spongy, with long roots at the nodes and numerous floating branches, the nodes glabrous or sometimes hispid; sheaths longer than the internodes, inflated except the uppermost on the branches, soft, papery, glabrous or sparsely papillose-hispid, auriculate; ligule 1-2 mm. long, brown; blades 10-27 cm. long, 1.2-2.5 cm. wide, thin, flat, scabrous; panicles 10-20 cm. long, shortly exserted; racemes numerous, mostly 3-5 cm. long, spreading or even reflexed, the rachis about 1.5 mm. wide, scabrous on the margins, acuminate, extending beyond the spikelets, naked for a short distance at the base; spikelets 1.4-2 mm. long, solitary, whitish, pubescent or glabrous, the glumes and sterile lemma pointed beyond the fruit; fruit 1.4-1.7 mm. long, smooth and shining.
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