Plants annuals or short-lived perennials; tufted. Culms 15-150 cm tall, 1-10 mm thick, dry to somewhat succulent, longitudinally grooved, glabrous. Leaves linear, veination conduplicate; sheaths open, glabrous, compressed laterally, often purple-streaked at the base; ligules membranous, long-ciliate; blades flat, midvein often white, adaxial surfaces minutely pubescent immediately distal to the ligule, glabrous elsewhere, margins strigillose. Inflorescences terminal, open, pyramidal panicles; rachises scabridulous, with 4-50 alternate, spikelike primary branches; primary branches to 7 cm, flexuous, axes scabridulous, with spikelets in 2 abaxial rows; pedicels shorter than 1 mm, cuplike, each with a single, smooth (occasionally scabridulous), terete bristle; bristles 4-12 mm, pale brown to black; disarticulation below the glumes. Spikelets dorsally compressed, with 2 florets; lower florets staminate; upper florets pistillate. Lower glumes 1/4-1/3 as long as the upper glumes, orbicular to triangular, 3-veined; upper glumes slightly shorter than the lower lemmas, often purple or green, 11-veined, acute; lower lemmas 5-veined, acute; lower paleas hyaline, about as long as the upper glumes, accrescent, thinly membranous at anthesis, becoming thicker and stiffer and about 3 times as wide as the lemma in fruit, keels clasping the upper floret at maturity; anthers 3, about 2 mm, orange; upper lemmas dorsally compressed, indurate, rugose, papillate, bases with a prominent germination flap, margins enclosing the edges of the upper paleas; upper paleas flat, indurate, papillate; stigmas bright red, plumose. Caryopses oblong obtuse, dorsally compressed; embryos about 1/3 as long as the caryopses. x = unknown. The origin of the name is obscure.