Plants in large clumps, with rhizomes 3-5 mm thick. Basal rosettes well-differentiated; sheaths pubescent; blades lanceolate. Culms 70-150 cm, robust, purplish; nodes glabrous or puberulent; internodes scabridulous to almost glabrous; fall phase branching from the mid- and upper culm nodes, developing numerous, well-separated, dense fascicles of many reduced blades and hidden secondary panicles. Cauline leaves 6-14; sheaths not overlapping, narrowing above midlength, sparsely to densely papillose-hispid, tops mottled with pale spots, margins ciliate, collars puberulent; ligules 0.5-1.2 mm, membranous; blades 12-25 cm long, 7-15 mm wide, linear, stiff, ascending to spreading, glabrous or sparsely pubescent, bases subcordate to constricted, margins scabridulous, apices long tapering, involute. Primary panicles 10-21 cm long, 6-13 cm wide, eventually well-exserted, with many spikelets; rachises and branches usually glabrous and mottled. Spikelets 2.2-2.8 mm long, 1-1.2 mm wide, ovoid-ellipsoid, often purplish, glabrous, rarely sparsely puberulent. Lower glumes 0.5-1 mm, acute; upper glumes and lower florets exceeding the upper florets, prominently 7-9-veined; lower florets sterile; upper florets acute to acuminate, with a minute tuft of hairs at the apices. 2n = 18.
Dichanthelium scabriusculum usually grows in wet, sandy, open sites, including shores, stream banks, swamps, and bogs. It is restricted to the eastern United States. The primary panicles develop from May to July, the secondary panicles, which are usually concealed within the sheaths, from July through November. Panicum aculeatum Hitchc. & Chase refers to what appear to be sterile hybrids with Dichanthelium clandestinum or robust subspecies of D. dichotomum; and P. bennettense W.V. Br. to hybrids with D. aciculare.
Culms few, erect, mostly 7-15 dm, glabrous to puberulent, often with a light-colored or mottled band of glandular tissue below each node; sheaths shorter than the internodes, glabrous or hispid, often mottled or white-spotted; ligule a minute membrane, usually with a band of short hairs just above it; blades elongate, mostly 10-25 cm נ6-15 mm, rather stiff, long-tapering from near the base to an involute tip, scabrous on the margins, glabrous on both sides or the lower puberulent beneath, at base glabrous or sparsely papillose-ciliate; primary panicle ovoid, with spreading or ascending branches, 8-15(-20) cm, half as wide, or wider; spikelets glabrous or minutely villosulous, ellipsoid to ovoid or lance-ovoid, pointed, 2.2-3.4 mm; first glume short and blunt, mostly less than one-third as long; second glume and sterile lemma pointed and surpassing the fr; autumnal phase loosely branched from the middle and upper nodes, the branches eventually forming dense tufts with much reduced blades and small panicles partly or wholly included in the sheaths; 2n=18. Wet, often sandy soil on the coastal plain; Conn. and N.J. to Fla. and Tex. (P. aculeatum; P. cryptanthum; Dichanthelium s.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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