Perennial rhizomatous herbs, rarely stoloniferous; rhizome creeping to ascendant. Roots fibrous. Leaves mostly basal; base sheathing, equitant; petiole absent; one species with an apical projection of the sheath (Pleea); lamina isobifacial, linear. Inflorescence terminal, a raceme, a spike or a single flower (Isidrogalvia flava); peduncle with 0-19 foliage leaves or bracts or foliage leaves grading into bracts up the peduncle. Flowers perfect, actinomorphic; sessile flowers or pedicels subtended by a bract. Calycular bracteoles just below the flower or half way on the pedicel rarely absent, usually 3, free or forming a tube. Tepals persistent, 6 in two similar whorls. Stamens 6 (or usually 9 in Pleea); anthers basifixed or dorisfixed; dehiscent longitudinally, introrse or latrorse. Ovary superior, stipitate or sessile; carpels 3, connate at base only or half to most of their length; ovules numerous; septal nectaries present or absent; style single with capitate stigma or 3 separate slightly recurved styluli. Fruit a capsule, septicidal or loculicidal, 2-10 mm long. Seeds arranged obliquely inside the locules, elliptical to narrowly fusiform, not black (no phytomelan), with appendages at one or both ends.