Perennial, 3–6 ft., or occasionally to 8 ft. high. Culms ascending from a sometimes long prostrate and copiously rooting base, stout, terete, usually many-noded and sheathed high up, simple or sparingly branched, glabrous, often waxy pruinose below the nodes. Leaf-sheaths tight, terete, rather firm, those of the prostrate bases decaying, glabrous and smooth or hirsute with tubercle-based hairs, mostly copiously bearded at the nodes; ligules a ciliolate rim; blades linear from a shortly and slightly constricted base, long-tapering to a slender point, from a few inches to over 1 ft. by 1/4– 2/3 in., flat, somewhat rigid or flexuous, glabrous or, rarely, more or less hirsute, margins scabrid, midrib slender like the primary lateral nerves (up to over 6 on each side) but little conspicuous. Panicle oblong to ovate-oblong in outline, subsecund or almost quaquaversal, often slightly flaccid, 4–8 (mostly 6) in. long; common rhachis terete to semiterete and more or less deeply channelled or triquetrous upwards, scabrid along the angles, glabrous. Racemes numerous, solitary or irregularly approximate, sometimes paired or in false whorls, shortly peduncled (the lowest) or subsessile, obliquely spreading, usually more or less flexuous, 2- or irregularly pluriseriate, 3 (rarely 5) to 1 in. long, mostly compound and then frequently interrupted or the upper, rarely all, simple and more or less dense, glabrous, greenish or tinged with purple; rhachis flat, herbaceous with a slender raised midrib up to 1/2 lin. wide, with projecting scabrid angles, villosulous at the base, otherwise glabrous, internodes of the more evenly dense racemes 1/2–1 lin. long; secondary racemes usually very short and 6–3-spiculate, or of the lowest racemes occasionally up to 1 in. long; pedicels solitary or paired, all very short, or if paired then the longer up to 1/2 lin. long, scaberulous with smooth discoid tips, frequently with a few setules. Spikelets laterally contiguous or discontiguous, those of the secondary racemes frequently imbricate, oblong to lanceolate-oblong, acute, somewhat flat on the back, 1 1/2–1 3/4 lin. long, glabrous. Glumes dissimilar; the lower broad-ovate, acute to subacute, from less than a third to not quite half the length of the spikelet, membranous, faintly 3–5-nerved, often tinged with purple; upper corresponding in outline and size to the spikelet, 5–7-nerved with few faint cross-nerves towards the tips. Lower floret ♂: valve as long as the upper glume and similar to it, but 5-nerved and more or less depressed on the back; valvule narrowly oblong, subacute, almost as long as the valve, with narrow flaps; anthers 1 lin. long. Upper floret hermaphrodite, slightly shorter than the spikelet (mostly 1 1/2 lin. long), oblong, subacute or very minutely apiculate, pale yellowish; valve and valvule crustaceous, very finely transversely wrinkled or almost smooth; stigmas blackish-purple, very conspicuous.
