Cyperaceae

Perennial or annual, monoecious or (very rarely) dioecious herbs, often with a grass-like or rush-like habit, tufted or rhizomatous, sometimes stoloniferous, rarely tuber-producing. Culms usually solid, rarely hollow between transverse septa, triquetrous to terete, occasionally 4–5-angular. Leaves basal and/or cauline, the outer basal ones often reduced to ± open sheathing scales; inner leaves and cauline ones (when present) embracing the culm with closed tubular sheaths; blade usually narrow and grass-like, occasionally reduced to a slender mucro; ligule present (membranous or ciliate) or absent. Inflorescence simple or compound, variously umbel-like, panicle-like or head-like, or reduced to a single spikelet; subtended by one or more leaf-like or occasionally glume-like or culm-like involucral bracts, the lowest ones often much exceeding inflorescence and resembling the leaves, the others gradually smaller, the upper ones (and sometimes all) small and glume-like. Spikelets either solitary or clustered, terete or compressed, with one to many flowers; rachilla sometimes winged. Flowers small and inconspicuous, bisexual or unisexual, each usually solitary within a bract (glume). Glumes arranged either distichously or spirally on the rachilla of the spikelet, one or more of the lower or upper ones often empty. Perianth reduced to hypogynous scales, bristles or hairs, very rarely subtepaloid or disk-like, often absent; stamens hypogynous, 3 or fewer, very rarely more, filaments free, anthers basifixed, oblong or linear, 2-locular, opening longitudinally; ovary superior, 1-locular with one erect ovule; style terminal, filiform or variously thickened at the base, ± deeply divided into 2 or 3 (rarely more) branches, rarely simple. Fruit a small seed-like nut, that from a 2-lobed style usually more or less 2-sided, and that from a 3-lobed style more or less 3-angular or terete. Amphicarpous spikelets rarely present, hidden amongst basal leaf-sheaths.