Sometimes included in Liliaceae.
Habit and leaf form. Herbs (tufted, more or less wiry); evergreen, or deciduous. Switch-plants; with the principal photosynthesizing function transferred to stems (phyllocladodes looking like real leaves). Leaves well developed. Perennial. Leaves basal. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; rhizomatous (may also lack a perennating organ). Self supporting, or climbing. Mesophytic, or xerophytic. Leaves alternate; spiral, or distichous; ‘herbaceous’, or leathery, or membranous; sessile; sheathing. Leaf sheaths not tubular; with free margins. Leaves edgewise to the stem, or with ‘normal’ orientation; simple. Leaf blades entire; solid; terete; linear, or lanceolate, or oblong, or ovate; linear (to filiform); parallel-veined; without cross-venules; sheathing. Leaves ligulate, or eligulate; without stipules. Leaf blade margins entire (scarious, at least towards the leaf bases). Leaf anatomy. Hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening absent. Roots. Aerial roots present (stilt roots at the nodes).
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (from septal nectaries).
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in spikes (condensed, globular). The terminal inflorescence unit cymose, or racemose (simple or compound). Inflorescences scapiflorous; terminal; inflorescence pedunculate or on a simple scape; young inflorescence surrounded by bracts; flowers may be dimorphic in the same head; with involucral bracts, or without involucral bracts; pseudanthial, or not pseudanthial. Flowers pedicellate, or sessile; bracteate (surround the young inflorescence, imbricate, scarious; flowers solitary within the bract, usually exceeding the bracts; outer bracts produced into filiform leaves; outer and inner bracts acute); bracteolate (linear); small, or medium-sized; regular; 3 merous; cyclic; pentacyclic, or tetracyclic. Perigone tube present. Perianth with distinct calyx and corolla (the whorls rather different), or of ‘tepals’; 6; 2 -whorled (3+3); isomerous; joined; petaloid; similar in the two whorls, or different in the two whorls; cream (rarely), or purple. Calyx (if the outer whorl so interpreted) 3; 1 -whorled; regular. Corolla (if the inner whorl so interpreted) 3; 1 -whorled; regular. Corolla members sometimes fringed. Androecial members definite in number. Androecium 3. Androecial members free of the perianth, or adnate (to the perianth); all equal; free of one another; 1 -whorled, or 2 -whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, 3. Stamens 3; all more or less similar in shape; isomerous with the perianth, or diplostemonous; at the base of the inner segments; alterniperianthial, or oppositiperianthial. Anthers clustered around the style; dorsifixed, or basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 3 carpelled. The pistil 3 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior. Ovary plurilocular; 3 locular; sessile. Gynoecium stylate. Styles 1; apical (or nearly so). Stigmas 1; 2–3 - lobed; capitate. Placentation axile. Ovules 2 per locule; arillate; campylotropous (generally), or anatropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; usually a capsule. Capsules loculicidal. Fruit 3 celled; 3–6 seeded. Seeds endospermic; arillate. Cotyledons 1. Embryo straight to curved.
Additional characters Pollen grains trichotomosulcate.