Erect, perennial, fleshy herbs. Leaves opposite-decsussate, crenate. Flowers large, pendent, in paniculate cymes. Sepals 4, connate in an inflated calyx tube. Petals 4, connate in a campanulate tube with short lobes. Stamens 8, in 2 series, filaments long, more or less equalling the corolla tube. Carpels 4, free, style exserted. Fruits many-seeded follicles.