Perennial or more rarely annual herbs. Leaves all radical, or cauline, and if so, opposite or alternate or whorled; stipules wanting. Flowers hermaphrodite, regular. Calyx usually inferior (half-superior in Samolus), 4–9-lobed or -partite. Corolla gamopetalous, with as many lobes as divisions of the calyx, lobes imbricate or contorted. Stamens equal in number to the corolla-lobes and page 429opposite to them, sometimes alternating with staminodia, inserted in the tube or at the base of the corolla; anthers 2-celled, introrse. Ovary superior (inferior in Samolus), 1-celled; style short or long, stigma usually capitate; ovules 2 or more, attached to a free central placenta. Fruit a 1-celled capsule, 2–6-valved or dehiscing transversely. Seeds 2 to many, minute, angular; albumen fleshy or horny; embryo small, transverse.

A small order, comprising 20 genera and 250 species; widely spread, but most plentiful on the mountains of the north temperate zone, rare in the tropics, the southern species comparatively few. The properties of the order are insignificant; but it includes many well-known garden-plants, as the primrose, oxlip, auricula, Chinese primrose, cyclamen, &c. The sole New Zealand genus is best represented in the Southern Hemisphere, but one of the species is almost cosmopolitan.