Annual, rarely perennial, with a few intravaginal innovations, usually 2–4 ft. high, occasionally much higher. Culms slender, erect, simple except for the inflorescence or with a long branch resembling the primary culm from one of the upper nodes, up to over 6-noded below the panicle, terete, glabrous, smooth. Leaf-sheaths terete, tight, striate, often flushed with purple below, glabrous, rarely loosely hairy, smooth, produced at the mouth into short auricles; ligules scarious, truncate, adnate to the auricles of the sheath, up to 1 lin. (rarely more) long; blades linear from a narrow base, long-tapering to a setaceous point, up to over 1/2 (sometimes 1) ft. long, 1–1 1/2 (rarely 2 1/2) lin. wide, rather firm, but flexuous, glabrous or sparingly hairy, pale green, turning reddish, scaberulous, particularly upwards, midrib slender, whitish, primary lateral nerves 2–3 on each side, very fine. Inflorescence an elongate or fastigiate obpyramidal and often ample spatheate panicle, 1/2–1 1/2 ft. long, of 5–7 frequently mixed tiers, approximate upwards and up to 5- (rarely 7-) rayed; lowest spathes like the preceding leaves, but with shorter, almost setaceous blades, the following rapidly approaching the spatheoles in shape and size; rays slender, filiform, those of mixed tiers usually very unequal, the compound ones often over-topping the next or 2 next tiers, the simple 3/4 to over 1 1/2 in. long. Spatheoles more or less scarious, linear-lanceolate, long-tapering upwards, acute to setaceously acuminate, glabrous or nearly appressedly hairy, 2–2 1/2 (rarely 3) in. long and at length tightly inrolled; peduncles finely filiform, at length slightly (rarely much) exceeding the spatheole or permanently shorter than it, puberulous or scaberulous towards the subcupular tips. Racemes 2-nate, one subsessile, the other with a short base, from less than 1 to 2 1/2 in. long, flexuous, villous, mostly laterally exserted from the spathe, at least before maturity; joints and pedicels clavate-cuneate, attenuated to a very slender base, tips very obliquely truncate, obscurely hollowed out, the pedicels often unequally 2-toothed, margins silky-ciliate, upper cilia up to 1 1/2 (rarely 2) lin. long. Sessile spikelets of all pairs heterogamous (or those of the subsessile more or less imperfect), laterally much compressed, loosely wedged in between joint and pedicel, narrowly linear in front view, 2 1/2–2 3/4 lin. long, pale yellowish-green; callus slender, subacute, 1/2 lin. long, shortly and densely bearded. Glumes equal, lower chartaceous along the keels, otherwise membranous, deeply and narrowly grooved between the narrow keels which are smooth below and scaberulous near the tips, minutely truncate, glabrous or very sparingly and minutely hairy upwards, nerves 2 or 3, very fine and close in each keel; upper glume submembranous, boat-shaped, acute, 1-nerved, eciliate, with a fine terminal bristle up to 4 lin. long. Lower floret reduced to an oblong hyaline ciliolate 2-nerved valve, 2 lin. long. Upper floret hermaphrodite: valve narrow, oblong, shortly 2-fid, up to 2 lin. long, ciliolate; awn 1–1 1/2 in. long, slender, column 1/2– 2/3 in. long, scaberulous, dark brown, bristle yellowish; valvule an oblong obtuse hyaline scale. Anthers 1 1/4 lin. long. Pedicelled spikelet ♂ or neuter, lanceolate-oblong, 2 1/2–3 lin. long, greenish or sometimes dull brown or purple; lower glume membranous, about 7-nerved, scaberulous and often more or less hairy upwards on the back (hairs up to 2 1/2 lin. long), with a fine terminal bristle up to 6 lin. long; upper glume subhyaline, acute, with or without a bristle, 3-nerved; valves of both florets hyaline, ciliolate, slightly shorter than the glumes, of the lower 2-, of the upper 3-nerved; the latter awnless.
