Syst. Nat. ed. 10,2: 855 (1759); Gen. Gram.: 287 (1986).
Description:
* Annuals or perennials. Culms with fibrous roots or rhizomatous, stoloniferous or not. Leaves flat or with involute margins.
* Inflorescence with exserted peduncle, composed of (1 -) 2-numerous spike-like racemes, arranged on all sides of main axis; rachis of racemes keeled on abaxial side. Spikelets alternate along keel, solitary or in unequally pedicellate pairs, usually crowded, articulate with pedicels.
* Spikelets sub orbicular to oblong, dorsally compressed, flat or concave on abaxial side, convex on ad axial side, 2-flowered, with lower lemma on abaxial side. Lower glume usually absent, minute when present; upper glume and lower lemma as long as spikelet or upper glume rarely shorter, herbaceous, lower palea absent. Upper lemma chartaceous-coriaceous with enrolled margins embracing upper palea; upper with a flat 2-veined back. Caryopsis tightly enclosed between upper palea and lemma.