Perennial, with a long stout creeping rhizome; innovations extravaginal. Culms erect or ascending, 5–15 ft. high, stout to very robust and bamboo-like, terete, up to 8 lin. in diameter, branched with the branches erect, up to 12- or more-noded, glabrous, scaberulous and finely striate below the inflorescence. Leaf-sheaths longer than the internodes, glabrous or loosely bearded at the mouth, quite smooth or the lower loosely pilose from tubercles and at length glabrescent, the lower broad and loose, prominently striate, firm and rigid; ligule reduced to a ciliate rim; blade linear, gradually passing into the sheath, tapering to a fine blunt tip, up to 1 1/2 ft. or more long, 2 1/2–9 lin. wide, flat, folded or rolled when dry, erect, rigid, green or subglaucous, glabrous or densely hairy at the back of the ligule, closely nerved and scaberulous above or quite smooth. False spike dense, cylindric, 3 1/2–12 in. long, 3 1/2–4 1/2 lin. wide (exclusive of the bristles), stramineous, greenish or tinged with purple; rhachis slender, finely ribbed, scaberulous, rather loosely to densely beset with the very minute stumps of the deciduous involucres; involucres sessile, spreading; bristles 12–25 to each involucre, very slender, scaberulous, of unequal length, free to the base, pallid, one much stouter than the rest and up to 8 lin. long, the remainder much shorter and up to 3 lin. long. Spikelets solitary, sessile within the involucre, lanceolate to narrowly ovate, acute and usually mucronate, 2–2 1/2 (rarely 3) lin. long, glabrous. Lower glume broadly elliptic or oblate, obtuse, 1/4– 1/3 lin. long, hyaline, nerveless, or suppressed; upper lanceolate to oblong, acute or obtuse, 1/3–1 lin. long, thinly membranous, 1–3-nerved or nerveless. Lower floret ♂ or barren, very rarely hermaphrodite: valve when flattened broadly ovate- to elliptic-oblong, obtuse or subacute, frequently mucronulate, as long or nearly as long as the spikelet, membranous, 5–9-nerved; valvule lanceolate-oblong, bifid, nearly as long as the valve, with minutely scaberulous keels, or suppressed. Upper floret hermaphrodite, lanceolate to lanceolate-oblong, acute or acuminate: valve when flattened broadly ovate- or elliptic-oblong, obtuse, mucronulate, as long as the spikelet, membranous, 5–7-nerved, finely scaberulous upwards; valvule lanceolate, slightly shorter than the valve. Lodicules minute. Anthers 1–1 1/4 lin. long, with glabrous tips. Styles connate or free nearly to the base.
