Rhizomatous, glabrous, often aquatic or semi-aquatic perennials (rarely annuals). Leaf-blades flat, glabrous and smooth to finely scabrous; sheaths often entire above nodes; ligules membranous. Inflorescence a panicle. Spikelets 3–many-flowered; glumes 2, unequal, hyaline, 1–2(–5)-nerved, shorter than lowest lemma; lemma 5–11-nerved, rounded dorsally; palea subequal to lemma.
About 40 species, cosmopolitan; 7 in Australia (4 naturalized), 5 in Victoria (4 naturalized).