Annual or perennial herbs, pubescent or glabrous. Leaves alternate, rarely almost subopposite, sessile or petiolate. Inflorescences terminal or axillary, a simple or branched scorpioid cyme, more or less straight or circinate; bracts absent (in Victoria). Flowers sessile or pedicellate (subsessile in Victoria); sepals 5, partly connate, sometimes elongating with age; corolla regular, 5-lobed, more or less cylindric, with scarcely spreading lobes, white, cream, purple or lilac, usually with a yellow throat; stamens included in corolla-tube, filaments very short, anthers often mucronate or acuminate with the apices free or cohering and forming a cone over the stigma, sometimes projecting from tube; ovary entire, 4-celled, style terminal, usually shorter than anthers; stigma conical. Fruit splitting into 4 mericarps or cohering in pairs, falling at maturity or retained within the sepals; mericarps smooth or rugose, glabrous or pubescent.
About 300 species, widespread from tropical to temperate zones; about 90 species in Australia (3 naturalized).
Increasingly now recognised in the seperate family Heliotropiaceae.