Tall, aquatic, monoecious annuals or perennials, sometimes with creeping rhizomes. Leaves flat. Inflorescence a large, terminal panicle with lower branches spreading or ascending and bearing pendent, early deciduous ♂ spikelets, upper branches ascending to erect at maturity, bearing ascending, tardily deciduous ♀ spikelets. Spikelets 1-flowered, falling entire from the pedicel; lower lemmas suppressed, rachilla modified to a callus-like structure at base of floret. Glumes obsolete, a small, collar-like ridge at tip of pedicel. ♂ spikelets: lemma membranous, 5-7-nerved, acuminate to shortly awned; palea ≈ lemma, 3-nerved; stamens 6. ♀ spikelets: lemma chartaceous, 3-nerved, tapering to a long slender awn; palea 2-keeled, the keels tightly clasped by lemma margins. Lodicules 2. Styles fused, stigma narrowly plumose. Caryopsis linear; embryo ½ length caryopsis to ≈ caryopsis; hilum ≈ caryopsis. Fig. 3.