Habit and leaf form. Herbs (tufted, graminoid). Perennial; plants with a basal concentration of leaves (more or less acaulescent), or with neither basal nor terminal concentrations of leaves; rhizomatous. Pachycaul. Mesophytic, or xerophytic. Leaves small to large; alternate; distichous; leathery, or modified into spines, or ‘herbaceous’; sessile; sheathing. Leaf sheaths not tubular; with free margins. Leaves simple. Leaf blades entire; rolled (sometimes), or solid; terete; acicular, or linear; narrowly to broadly linear (to filiform or gradually tapering to the apex); parallel-veined; without cross-venules; basal margins membranous to scarious or often split into fibres, distinct sheathing. Leaves without stipules. Vegetative anatomy. Plants without silica bodies. Leaf anatomy. Hairs present, or absent (or warty or papillose). Extra-floral nectaries absent. Stem anatomy. Secondary thickening anomalous; from a single cambial ring.
Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants dioecious. Female flowers with staminodes (6 staminodes present). Male flowers with pistillodes.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, or in panicles, or in spikes. Inflorescences scapiflorous, or not scapiflorous; cymose clusters or spikes; male and female inflorescences similar or dissimilar. Flowers pedicellate; bracteate (outermost ones subtend clusters of flowers, others subtend individual flowers); ebracteolate; small; regular; 3 merous; cyclic. Perigone tube present, or absent. Hypogynous disk absent. Perianth of ‘tepals’; 6; 2 -whorled; isomerous; petaloid; similar in the two whorls, or different in the two whorls; green (greenish), or white, or cream, or yellow, or purple (purplish); fleshy, or non-fleshy. Fertile stamens present, or absent. Androecial members definite in number. Androecium 6. Androecial members free of the perianth (outer 3 sometimes), or adnate (on the perianth at various levels); markedly unequal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 6 (in 2 whorls); all more or less similar in shape; diplostemonous; outer 3 on the receptacle or rim of the perianth tube, inner 3 on the perianth close to or distant from the outer stamens; filantherous, or with sessile anthers (sometimes). Anthers dorsifixed; dehiscing via longitudinal slits; introrse. Pollen shed as single grains. Fertile gynoecium present, or absent (male flowers). Gynoecium 3 carpelled. The pistil 3 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 3 locular; sessile (more or less). Gynoecium non-stylate, or stylate. Styles 1; attenuate from the ovary, or from a depression at the top of the ovary; apical. Stigmas 1; 3 - lobed. Placentation axile. Ovules 1 per locule; non-arillate; anatropous to campylotropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Seeds endospermic. Embryo well differentiated. Testa without phytomelan.
Additional characters Pollen grains sulcate, or spiraperturate (or irregular).