Plants annual or perennial; tufted or cespitose, not rhizomatous. Culms 10-200 cm, herbaceous, not branching at the upper nodes; basal branching usually intravaginal; prophylls shorter than the sheaths. Leaves mostly basal; cleistogenes usually not developed; sheaths open; auricles absent; ligules membranous, sometimes stiffly so, upper and lower ligules similar or upper ligules longer than those below; blades prominently ribbed, usually tightly convolute when dry. Inflorescences terminal panicles, usually contracted. Spikelets 12-90 mm, with 1 floret; rachillas not prolonged beyond the base of the floret; disarticulation above the glumes, beneath the floret. Glumes much longer than the floret, hyaline to membranous, usually acuminate, 1-3-veined; florets 3-27 mm, terete to slightly laterally compressed; calluses (1)1.5-6 mm, sharp or blunt, antrorsely hairy; lemmas coriaceous to indurate, tan to brown, smooth, glabrous or hairy, hairs sometimes uniformly distributed, sometimes in lines, margins flat, slightly overlapping at maturity, apices awned, lemma-awn junction evident; awns 50-500 mm, persistent, usually once- or twice-geniculate, sometimes plumose in whole or in part, basal segment often strongly twisted; paleas from shorter than to subequal to the lemmas, glabrous, 2-veined, not keeled, flat between the veins, apices sometimes scarious, sometimes similar in texture to the body; lodicules 2 or 3, glabrous or pilose; anthers 3; styles 2(3,4), free at the base, if 3 or 4, then 1 or 2 distinctly shorter. Caryopses fusiform, not ribbed. x = 11. Name from the Latin stipa, 'oakum' (a loose bunch of fibers), alluding both to the feathery inflorescences and the use of Stipa tenacissima L. [ = Macrochloa tenacissima] as a source of cordage.