Habit and leaf form. Herbs (caespitose). Perennial. Leaves basal and cauline. Plants with a basal concentration of leaves (more or less acaulescent), or with neither basal nor terminal concentrations of leaves; rhizomatous (short). 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; acicular, or linear; linear (gradually tapering to the apex); parallel-veined; without cross-venules; closely sheathing the stem; sheath 7-nerved; margins scarious, often splitting away. Leaves without stipules. Vegetative anatomy. Plants without silica bodies. Leaf anatomy. Hairs present. Extra-floral nectaries absent.
Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants dioecious. Female flowers solitary. Male flowers aggregated in ‘inflorescences’; with pistillodes.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, terminal; the male inflorescence in cymes. Inflorescences scapiflorous, or not scapiflorous; terminal; infloresence small, of 1–3 male flowers. Flowers pedicellate; ebracteate; ebracteolate; small; regular; 3 merous; cyclic. Perigone tube present, or absent. Free hypanthium short. Hypogynous disk absent. Perianth of ‘tepals’; 6; 2 -whorled; isomerous; petaloid (in male flowers); similar in the two whorls, or different in the two whorls; white; fleshy, or non-fleshy. Fertile stamens present, or absent. Androecial members definite in number. Androecium 6. Androecial members adnate; all equal; free of one another; 2 -whorled. Androecium exclusively of fertile stamens. Stamens 6 (in 2 whorls); all more or less similar in shape; diplostemonous; on the perianth. Anthers dorsifixed to basifixed; 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. Gynoecium 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, or indehiscent; a capsule, or capsular-indehiscent; 1 seeded. Seeds endospermic. Embryo well differentiated. Testa without phytomelan.