Annuals or perennials, often aquatic. Leaf-blades linear; ligule a ciliate rim Inflorescence composed of several to many short straight racemes spaced along a common axis and ± appressed to shallow hollows in it; rhachis triquetrous or winged, usually ending in a point, bearing single imbricate spikelets, their lower glume abaxial. Spikelets ovate, dorsally compressed, glabrous; lower glume much shorter than the spikelet; upper glume mostly almost as long as the spikelet; lower floret male or barren, its lemma resembling the upper glume; upper lemma crustaceous, acute, clasping only the edges of the palea; upper palea acute, the tip briefly reflexed. Caryopsis elliptic, dorsally compressed.