Herbs, sometimes shrubby, with often succulent stems. Leaves alternate, opposite or whorled, simple. Inflorescences axillary, less often terminal or solitary. Flowers bisexual, zygomorphic. Sepals 3(5), the posterior large, petaloid and nearly always spurred, the lateral small. Petals 5, the anterior one always large, flat or helmet-shaped; the 4 lower ones usually connate in pairs, usually deeply 2-lobed. Stamens 5. Ovary superior, 5-locular. Fruit a capsule.