Plants perennial; cespitose, not rhizomatous. Culms 100-250 cm, erect, smooth, glabrous, uppermost node often exposed; basal branching intravaginal; prophylls exceeding the subtending leaf sheaths, awned, ciliate or glabrous. Leaves basally concentrated; cleistogenes not developed; sheaths open to the base, smooth, glabrous except at the throat; auricles absent; ligules membranous, rounded, abaxial surfaces densely pubescent, margins ciliate; blades flat to involute, abaxial surfaces smooth, adaxial surfaces scabrous or hirtellous. Inflorescences panicles, nodding, open. Spikelets 25-32 mm, with 1 floret; rachillas not prolonged beyond the base of the floret; disarticulation above the glumes, beneath the floret. Glumes lanceolate, exceeding the floret, 3-veined; florets 14-16 mm, terete to laterally compressed; calluses sharp, strigose; lemmas coriaceous, evenly pubescent, hairs 1-2 mm, margins flat, overlapping at maturity, apices bifid, awned from between the teeth, teeth scarious; awns persistent, twice-geniculate, first segment twisted, terminal segment straight; paleas subequal to or longer than the lemmas, membranous, dorsally pubescent, veins forming 2 awnlike extensions; lodicules 3, glabrous, lanceolate, posterior lodicule larger than the lateral lodicules; anthers 3, penicillate; ovaries glabrous; styles 2. Caryopses fusiform; hila linear, about as long as the caryopses. x = 12. Named for the Celts, the genus being most abundant in the portion of the Iberian Peninsula to which the Celts were driven by the Romans.