Annual, biennial, or perennial herbs, caulescent or acaulescent, with a taproot or spreading underground parts. Basal rosette present or absent; leaves alternate, stipules absent. Flowers 4-merous, actinomorphic, in axils of upper leaves, opening near sunset or near sunrise; floral tube well-developed and prolonged beyond the ovary, deciduous after anthesis. Petals yellow, purplish, or white; stamens 8, anthers versatile, the sporogenous tissue in each locale undivided; pollen shed singly; stigma deeply 4-lobed. Capsule many-seeded, sessile or pedicellate, mostly straight, terete or somewhat 4-angled, loculicidally dehiscent or indehiscent. Seeds naked, in 1 to several rows in each of the 4 locules. Basic chromosome number, x = 7.