Culms glabrous, when submersed elongate and little branched, when terrestrial tufted from the base; sheaths loose, papillose-hispid to glabrous; lf-blades tapering at both ends, thin, (5-)8-12(-20) cm, often 1 cm wide or more; racemes numerous (usually 20-50), crowded, spreading or ascending, 2-4 cm; rachis 0.8-2 mm wide, its acuminate tip surpassing the uppermost spikelet by 1-3 mm; spikelets solitary (not paired), elliptic, acute, 1.1-1.5 mm; glume and sterile lemma 2-veined near the margin, the glume finely glandular-villosulous; 2n=20. Shallow water, swamps, and muddy shores; widespread in s. U.S., n. on the coastal plain to se. Va. and in the Mississippi Valley to w. Ky., s. Ind., c. Ill., and c. Mo. (P. mucronatum; P. repens, misapplied)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.