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.