Annual, up to over 1 1/2 ft. high. Culms fascicled or single, suberect from a geniculate base or erect, slender, terete, glabrous and very smooth, about 5-noded, branched from the base or above it, with the lowest 1 or 2 internodes elongated (2–5 in.), and the branches suberect or obliquely spreading. Leaf-sheaths rather thin, striate, often slipping off the internodes, pale or the upper subherbaceous, quite glabrous or with long fine spreading tubercle-based hairs; ligules a fringe of short white hairs; blades linear to sublanceolate-linear from a more or less rounded base, long-tapering to a fine point, 3–6 in. by 2–3 1/2 lin., flat, thin, green or slightly glaucous, quite glabrous or with a few spreading marginal hairs at the very base, margins scaberulous, primary lateral nerves 3–4 on each side with numerous very fine secondary ones between them, midrib slender, rather prominent downwards on the back. Panicle at length more or less exserted, broad-ovate in outline, 3–6 in. by 2–5 in., of 4–6 solitary at length much spreading very lax racemes; common axis slender, terete below, more or less flattened upwards with scabrid angles, glabrous, terminating with a spikelet; racemes slender, the lower and intermediate 4–2 in. long, at length rather stiff, sessile, simple or the longest compound downwards with scanty secondary racemes up to over 1 in. long; rhachis very slightly wavy, triquetrous, or rounded downwards on the back, up to 1/5 lin. wide, scabrid along the angles, glabrous; pedicels paired or upwards solitary, filiform, angular, scaberulous, glabrous or rarely with a few fine long spreading hairs. Spikelets or pairs of spikelets or secondary racemes distant by 4–10 lin., or the lowest by almost 1 in., hence very loosely scattered; spikelets obovoid-oblong, subobtuse or apiculate, turgid, distinctly narrowed at the base, 3/4–2 lin. long, rather green and quite glabrous, very similar in structure to those of B. ramosa and B. regularis, but the lower glume slightly larger, usually very acute and frequently 3-nerved or sub-5-nerved (with the outer side-nerves very short), the valvule of the barren floret more developed with distinctly winged keels and the valve and valvule of the fertile floret coriaceous-crustaceous and strongly (often acutely) transversely rugose, at length turning dull brown.
