Aquatic perennial; culms spongy, rooting at nodes. Sheaths longer than the internodes, long-pubescent, becoming glabrous, auriculate at apex; blades 10-27 cm long, 10-25 mm wide, scabrid and with fewer long trichomes. Panicles 10-20 cm long, the racemes spreading or reflexed, 3-6 cm long; rachis winged, the wing wider than spikelets, scabrid throughout; spikelets solitary, plano-convex or sometimes convex on both sides, oblong-elliptic to narrowly ovoid, 1.5-2 mm long, glabrous to short-pubescent, whitish; first glume lacking; second glume and sterile lemma exceeding fruit. Fruits 1.4-1.7 mm long, white, smooth. Shattuck 403.