Robust annual; ligule membranous; blades large and soft; panicle erect, to 6 dm, the staminate branches widely spreading, the pistillate at first erect, at anthesis ascending; staminate spikelets pendulous, 6-11 mm, stramineous to purplish, glabrous or nearly so, the lemma awnless or with an awn to 3 mm; pistillate spikelets linear, with an awn to 7 cm, the lemma thin and membranous, minutely scabrous all over, the exposed surface of the palea likewise roughened; some spikelets in the pistillate part of the infl sterile and abortive, the lemma subulate, less than 1.5 mm wide, often twisted, tapering insensibly into the awn; 2n=30. S. Que. and coastal states from Me. to Fla. and La., irregularly inland in n. N.Y. and from w. Lake Erie to Wis. and s. Ill. The widespread var. aquatica, southern w. r., is robust, (1)2-3(-5) m, with lvs mostly 2.5-5(-8) cm wide, the infl 2.5-6 dm, its pistillate lemmas with an awn mostly 2-7 cm. The var. brevis Fassett, estuarine w. r., occurring along the St. Lawrence estuary in Que., is smaller, to 1 m, with lvs to 1.5 cm wide and small, few-branched infls 1-2.5 dm, the pistillate lemmas with an awn under 1.5 cm.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.