Herbs, dioecious or in two species female only and parthenogenetic, caespitose or rhizomatous, perennial, the base pubescent or villous; cluster and sand-binding roots present. Cataphylls appressed, enwrapping the culm bases, often glossy and glabrous. Culms terete or flattened, glabrous or pubescent, smooth or striate or tuberculate, straight or flexuose, branched or with short lateral verticillate branchlets; internodes one to numerous, when more than one with persistent, appressed or lax sheaths; culm hairs multicellular, branched or simple. Spikelets solitary or in clusters, terminating culms or short lateral inflorescence branches or in axils of upper sheaths. Glumes especially in females often with a rigid, dark mucro or apical spine. Male spikelets several-to many-flowered, glumes mostly numerous, all fertile or lower glumes sterile. Female spikelets 1–several-flowered, usually with sterile lower glumes. Male flowers with (1–) 5 (–6) tepals, 2 outer tepals keeled, 3 inner tepals flat, stamens 3, anthers exserted. Female flowers lacking tepals or with 1–6 tepals; ovary 1-locular; style single, unbranched, often rather stout, mostly stigmatic; in parthenogenetic species the style not developed and the fruit closely enwrapped with the uppermost glume. Fruit a small nut, with 2 pale lateral longitudinal lines marking the carpel margins, and a conical or rounded stylar beak or the beak not persistent; pericarp ranging from hard and woody to soft and hyaline; shed with persistent short stipe and tepals if present; in some species shed enwrapped in a striated glume. Seeds smooth with subangular cells arranged in lines or in an irregular pattern. Culm anatomy: chlorenchyma continuous, of 1 or 2 layers of short or elongated peg cells, mostly with inward-projecting epidermal cells partially lining substomatal cavities, walls of epidermal cells thickened on outer wall and outer part of radial walls; radial walls often sinuous; often with radially elongated epidermal cells forming mounds on the culm surface; culm with a central cavity or with vascular bundles in the central ground tissue and multiple lacunae in the ground parenchyma, or the central tissue sclerenchymatous and with scattered vascular bundles throughout.
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