Annual or perennial herbs, tufted or rhizomatous, glabrous. Leaves flat and grass-like, or tubular or laterally compressed with internal septa, or channelled, or terete and stem-like, or reduced to basal sheaths. Inflorescence a many-flowered cyme, much-branched or condensed to a compact head, or flowers rarely few or solitary. Flowers usually hermaphrodite, sessile or pedicellate. Tepals 6, rarely 4, lanceolate, the outer usually longer, slightly more rigid with narrow membranous margin, inner with broader membranous margin. Stamens 6, 3, or variable 3-6. Ovary unilocular, or triseptate, or trilocular. Seeds numerous, often tailed at one or both ends. A cosmopolitan genus of c. 300 spp. Native spp. 16, adventive 31.

Infl. a many-fld cyme, much-branched or condensed into a compact nead, or fls rarely few or solitary. Fls hermaphrodite, rarely unisexual, sessile or pedicellate, bractlets 2 or 0. Tepals lanceolate, acute, the outer us. longer, slightly more rigid, with narrow membr. margin, the inner occ. almost obtuse, with broader membr. margin. Stamens 6, 3, or variable 3–6. Ovary unilocular, or triseptate, or trilocular. Seeds ∞, often tailed at one or both ends, testa us. finely sculptured. Annual or perennial herbs, tufted or rhizomatous, glab. Lvs flat and grasslike, or tubular or laterally compressed with internal septa, or channelled, or terete like the stems, or reduced to bladeless sheaths; sheath often produced above into 2 obtuse auricles. A cosmopolitan genus of c. 300 spp. Of the 16 N.Z. spp., 12 are found also in Australia and two of these have been recorded from elsewhere in the Pacific; one is an austral circumpolar sp. Three N.Z. spp. are endemic.