Terrestric or aquatic annuals or perennials, 5-40 cm. Rhizome short or creeping. Stem erect or creeping (or floating), usually terete. Leaves from reduced pseudolateral sessile spikes in globose head; bracts to several, leaf-like and exceeding inflorescence. Spikes with to c. 30 spirally arranged glumes. Flowers bisexual, perianth bristles 0; stamens 1-3; stigmas 2-3. Nut 0.5-2 mm, trigonous or lenticular.