Loosely tufted annuals or perennials. Leaf-sheath open at maturity. Ligule membranous. Leaf-blade flat or convolute, scaberulous. Culm erect, or ± geniculate at base. Inflorescence a lax or contracted panicle; branches and pedicels slender. Spikelets 3-many-flowered, ovoid or broadly triangular, compressed, pendent or erect; florets closely imbricate; disarticulation above glumes and between florets; rachilla prolonged, glabrous. Glumes ± equal, persistent, concave, ovate-orbicular or lanceolate, spreading, < adjacent lemmas, at least the upper cordate at base. Lemma 5-many-nerved, broad, faintly keeled or rounded, usually deeply concave, orbicular or suborbicular, gibbous, usually coriaceous and shining centrally, sometimes cordate at base, margins wide, scarious. Palea < lemma, orbicular, obovate or lanceolate; keels 2, well-separated, usually narrowly winged and minutely ciliolate. Callus glabrous. Lodicules 2, membranous. Stamens 3, or 1 (South American spp.). Ovary glabrous, styles free to base. Caryopsis dorsally rounded, ventrally flattened; embryo small; hilum variable.