Plants annual; tufted or culms solitary. Culms 7-70 cm, erect to decumbent. Leaves cauline; sheaths open; auricles vestigal or absent; ligules membranous; blades flat. Inflorescences panicles, contracted or spiciform; branches appressed to ascending. Spikelets laterally compressed, solitary, with 1 bisexual floret; rachillas prolonged as bristles or absent; disarticulation above the glumes. Glumes unequal, exceeding the florets, 1-veined, basally subcoriaceous and gibbously swollen, distally membranous, narrow, acuminate to attenuate, unawned; calluses short, blunt, glabrous; lemmas membranous, pubescent or glabrous, 5-veined, lateral veins usually faint, apices more or less truncate and denticulate, unawned or awned in the upper 1/3, awns shorter or longer than the lemmas, geniculate, unawned and awned lemmas present in the same panicle; paleas subequal to the lemmas, hyaline, 2-veined, bifid; lodicules2, membranous, glabrous, entire, unlobed; anthers 3; ovaries glabrous. Caryopses slightly adhering to the lemmas and/or paleas, hila short. x = 7. Name from the Greek gastridion, small pouch, alluding to the gibbously swollen glumes.