Perennial, diffuse or erect herbs. Leaves
exstipulate, opposite or alternate. Flowers solitary or in terminal cymes,
usually showy. Sepals connate in a narrowly campanulate, 5-ribbed calyx, deeply
5-fid, lobes acute, often with scarious edges. Petals 5, connate in a
salver-shaped corolla, tube slender, lobes equal, obovate, orbicular or
obcordate. Stamens 5, included, unevently adnate to the corolla tube. Carpels
3, syncarpous, ovary superior, 3-locular, 1 or 2 ovules in each locule, styles
simple with shortly 3-fid apex. Capsules ovoid, 3-valved.