Annual, 3 to over 12 in. high. Culms very slender, glabrous and smooth, simple from the uppermost node but usually branched from the two preceding nodes, in dwarf specimens the lower internodes arrested, hence the plants scantily tufted with short flowering branches from the base and a 1-noded primary culm rising above them; in elongated specimens the lower 2 or 3 nodes more or less distant, hence the branches also more or less remote and distinctly above the base, the corresponding internodes stouter and spongy, the primary culm and often also the elongated branches geniculate. Leaf-sheaths rather loose and wide, uppermost tight, all thin with minute auricles or shoulders, quite glabrous and smooth; ligules membranous, truncate, very short; blades narrowly linear from an equally wide base, tapering to a minute callous point, 1 1/2 to over 6 in. by 1/2– 3/4 lin., flat or involute, thin, weak, green, loosely papillose to glabrous on the nerves above, midrib and lateral nerves (2 or 3 on each side) very delicate. False spikes erect on a finely filiform often long-exserted peduncle, 2/3–2 in. by 1 1/2–1 3/4 lin., continuous and dense or slightly interrupted; axis very slender, 1/6– 1/4 lin. in diam.; pedicels fine, with few minute hairs or slightly scaberulous, tips discoid. Spikelets ovate to ovate-oblong, symmetrical, first acute, then obtuse, 3/4– 7/8 lin. long, widely gaping when mature and shedding the false fruit, tardily deciduous, olive-green mostly with dark purple nerves and tips, glabrous. Glumes very thin, finely nerved; lower broad-ovate, subobtuse or obtuse, over half to three-quarters the length of the spikelet, 3–5-nerved; upper 5–7-nerved. Lower floret barren: valve very like the upper glume and of the same length, 5–7-nerved; valvule linear, three-quarters the length of the valve or more reduced with narrow upwards evanescent flaps. Upper floret hermaphrodite, oblong, subobtuse, 1/2 lin. by 1/4 lin., brownish when ripe, polished.
