Herbs, usually perennial, often rhizomatous. Stems usually solid, often 3-angled. Leaves usually linear, some or all often reduced to basal sheaths. Flowers hermaphrodite or unisexual, each in the axil of a glume (bracteole), arranged in spikelets; inflorescence various, a simple or compound irregular umbel or panicle, or a capitate cluster of spikelets or a solitary terminal spike; commonly with 1 to several setaceous to leaf-like involucral bracts. Perianth of bristles, scales, hairs or 0. Stamens 3-(2-1), rarely 4-6. Ovary superior, 1-locular; style-branches 2 or 3; ovule solitary. Fruit a nut, indehiscent. Cosmopolitan, c. 90 genera and c. 4000 spp.

Fls hermaphrodite or unisexual, each in the axil of a bracteole (glume) and arranged in spikelets; infl. various, a simple or compound irregular umbel or panicle, or a capitate cluster of spikelets or a single terminal spike; commonly subtended by 1 to several involucral lvs. Per. of bristles, scales, hairs or 0. Stamens 3–(2–1), rarely 4–6; anthers basifixed, 2-celled, connective us. ± produced into a small point. Ovary superior, 1-locular; style-branches 2 or 3; ovule solitary, anatropous. Fr. nutlike, ind.; seed with cop. endosperm. Us. perennial, often rhizomatous herbs. Culms us. solid, often triquetrous. Lvs us. linear, some or all often reduced to sheaths. Cosmopolitan, c. 90 genera and c. 4,000 spp.