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Annuals or perennials, tufted or sometimes with creeping rhizomes or stolons. Leaf blades flat or rolled, linear to narrowly lanceolate; ligule a line of hairs. Inflorescence an open or contracted panicle, rarely spikelike. Spikelets with 1 floret, subterete, not compressed or keeled, glabrous; rachilla disarticulating above glumes; glumes usually shorter than lemma, unequal, membranous, deciduous or persistent, 1-veined or veinless, apex obtuse, acute or acuminate; lemma elliptic to narrowly ovate, thinly membranous, 1–3-veined, glabrous, rounded on back, awnless; palea equaling or shorter than lemma, depressed between veins and often splitting lengthways as grain grows. Stamens 2–3. Grain globose to ellipsoid, rounded or truncate, pericarp free, commonly swelling when wet and expelling the grain, which often adheres to spikelet apex. x = 9, 12.
Spikelets 1-fld, articulated above the glumes; glumes lanceolate to ovate, 1-veined, from much shorter to somewhat longer than the lemma; lemma membranous or herbaceous, rounded on the back, veinless or 1(3)-veined, obtuse to acuminate, awnless; palea about as long as the lemma or longer, of similar texture, usually conspicuous and in some spp. wider than the lemma; grain in most spp. soon separating from the lemma and palea, falling free; pericarp free from the seed; annual or perennial grasses with narrow, often involute lvs, minute or no ligule, and open or contracted panicles of rather small spikelets. 100, mostly of warm reg., esp. in the New World.
Spikelets 1-flowered, fusiform, glabrous or rarely puberulous (with a rhachilla extension in 35. S. fibrosus and 36. S. subtilis); glumes deciduous, awnless or rarely mucronate, the superior usually longer than the inferior and resembling the lemma; lemma thinly membranous or rarely hyaline, 1-nerved or rarely 3-nerved, entire, awnless; palea resembling the lemma but 2-nerved, depressed between the nerves and often splitting longitudinally as the grain swells; anthers 2–3.Grain rotund to elliptic, rounded or truncate at the apex; pericarp free, commonly swelling when wet and expelling the seed to the tip of the spikelet.
Annuals or perennials. Culms usually erect. Inflorescence a panicle open or contracted, rarely spiciform, exserted from the uppermost sheath, the branches whorled or not. Spikelets small, fusiform, nearly always glabrous, awnless; palea 2-nerved. Fruit rounded or truncate at the tip, not beaked, the pericarp commonly swelling when wetted and ejecting the seed.
Spikelets 1-flowered, disarticulating above the glumes; glumes awnless, sub-equal or usually unequal, the second often as long as the spikelet; lemma 1-nerved, acute to obtuse, awnless; palea as long as or sometimes longer than the lemma. Annuals or perennials with open or contracted, often spike-like, panicles of small spikelets.
Inflorescence a panicle, open or contracted, rarely spiciform, exserted from the uppermost sheath, the primary branches whorled or not, rarely those of the lowermost whorl sterile.
