Herbs, monoecious, perennial, shortly or extensively rhizomatous, forming dense tussocks or extensive patches, rush-like, with sand-binding roots. Culms photosynthetic, unbranched with 1–3 distal inflorescence branches, terete, striate. Cataphylls well-developed, scarious. Leaves on the culm reduced to one (at the base of the peduncle) or few (3 or 4) scarious sheaths; sheaths open and overlapping at the base. Inflorescence of one or few compact cylindrical or ovoid spikes terminating culm or inflorescence branches. Spikes with zones of female and male flowers alternating once or twice along spike axis, the basal zones mostly female. Flowers spirally arranged in 5 ranks, on very short pedicels, subtended by a dark brown, rigid or scarious, ovate glume; glumes all or mostly subtending flowers. Perianth of 6 scarious to hyaline tepals in two whorls, dorsiventrally compressed, the outer two lateral segments folded and keeled, keel pubescent in male flowers. Male flowers with a minute pistillode and 4 or 6 stamens; filaments free, slender; anthers tetrasporangiate, dorsifixed, 2-lobed, latrorse, dehiscing by longitudinal slits. Female flowers with staminodes; ovary superior, free, 2-or 3-locular with 2 or 3 feathery, mostly stigmatic styles; each loculus with a solitary pendulous ovule. Fruit a capsule or a small nut (structurally an achene) shed with attached tepals and very short pedicel. Culm anatomy: with deep narrow grooves extending into the chlorenchyma, enlarged epidermal cells overhanging the grooves, thick sclerenchyma caps on the ridges between the grooves and with stomates and accompanying sclereids at the base or sides of the grooves; ridges with or without a central sclerenchyma rib.
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