Perennial, up to over 3 ft. high (to 6 ft. according to Hens), densely tufted on a short rhizome with intra- and extra-vaginal innovations and short closely noded stolons; rhizomes, stolons and cataphylls quite glabrous. Culms erect or more often slightly geniculate at the base, rather stout below, moderately so upwards, simple, usually 5–6-noded, glabrous and smooth except close to the inflorescence, there more or less scabrid and hairy, lower internodes 2–3 in. long, much compressed to ancipitous and 2–2 1/2 lin. wide, hardly striate, the following longer and gradually more terete, the uppermost slender, up to 1 1/2 (rarely 2) ft. long, finely striate. Leaf-sheaths firm, quite glabrous and smooth, laterally compressed and keeled, the basal very much so, often conspicuously flabellate-imbricate, pale and more or less persistent, with the blades often disarticulating, 1–6 in. long, 2–3 1/2 lin. wide (in profile), finely or obscurely striate, upper gradually longer, more herbaceous, more or less equalling the internodes or the uppermost very much shorter; ligule reduced to a densely ciliolate rim; blade linear from an equally wide base, tapering to an acute or subacute point, tightly folded and acutely keeled or, particularly in the upper leaves, unfolding and quite flat, 4–10 in. long by 2–4 lin. wide (when unfolded), dull green to glaucous, somewhat succulent, glabrous, margins slightly rough upwards only, midrib very much compressed downwards, inconspicuous except in cross-section, primary lateral nerves differentiated below only, up to over 6 on each side. Inflorescence a continuous and very dense or here and there loosened cylindric false spike, 4–10 in. long by 1 1/2–2 (rarely 2 1/2) lin. wide (exclusive of the bristles), fulvous to brownish; axis obscurely angular, tomentellous, slender; branches puberulous, reduced to sessile involucres supporting clusters of 2–3 perfect or partly imperfect spikelets or a solitary spikelet; bristles fine, 7–10 to each involucre, 2–2 1/2 (rarely 3) lin. long, scaberulous, concolorous; pedicels very short with minute discoid tips. Spikelets elliptic-oblong and acutely but minutely apiculate in back view, more or less semi-elliptic in profile, 1 lin. long by 1/2 lin. wide or slightly over (back and side view), glabrous, pale or almost white or suffused with livid purple, particularly the upper floret. Glumes very thinly membranous, sometimes almost hyaline; lower rotundate-ovate, subobtuse to almost acute, less than half the length of the spikelet, 3- (rarely 5-) nerved; upper similar but half the length of the spikelet or somewhat over and 5-nerved. Lower floret ♂: valve of the size and outline of the spikelet, dorsally flattened or depressed longitudinally, 5-nerved; valvule elliptic-oblong, as long as the valve or almost so, with marginate keels; anthers 1/2– 2/3 lin. long. Upper floret hermaphrodite: valve elliptic-oblong, subapiculate, as long as the lower or almost so, pale or the valve more usually purplish-brown over the exposed part, finely transversely rugose.
