Sometimes included in Liliaceae.
Habit and leaf form. Herbs (tufted); evergreen, or deciduous. ‘Normal’ plants, or switch-plants; the switch forms with the principal photosynthesizing function transferred to stems. Leaves well developed, or much reduced (scale leaves). Perennial. Leaves basal. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; rhizomatous. Self supporting, or climbing. Winter-wet swampy sand. 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; parallel-veined; without cross-venules; sheathing, brown, pungent. Leaves ligulate, or eligulate; without stipules. Leaf blade margins entire. Leaf anatomy. Hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening absent.
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 racemes (elongated). The terminal inflorescence unit cymose, or racemose (simple or compound). Inflorescences scapiflorous; terminal; scape bracteate; inflorescence simple, as long as the leaves, about 50 flowers; with involucral bracts, or without involucral bracts; pseudanthial, or not pseudanthial. Flowers pedicellate (slender, filiform); bracteate (usually 3 per scape, brown, linear-lanceolate, scarious, acute; 1 subtends each flower, small, linear or lanceolate, scarious); bracteolate (1 subtends each flower, 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; 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 6. Androecial members free of the perianth, or adnate (to the perianth); markedly unequal (perfect stamens with larger filaments); free of one another; 1 -whorled, or 2 -whorled. Androecium including staminodes (with little or no pollen). Staminodes 3 (opposite the outer segments). Stamens 3; distinctly dissimilar in shape; isomerous with the perianth, or diplostemonous; at the base of the perianth opposite the inner segments; alterniperianthial, or oppositiperianthial. Anthers cohering (staminodia free); basifixed; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged (connective produced into a single tube). 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; 1 seeded (per locule). Seeds endospermic; arillate. Cotyledons 1. Embryo straight to curved.
Additional characters Pollen grains trichotomosulcate.