Herbs, sometimes vines, shrubs or trees, with opposite leaves, simple, pinnate venation, exstipulate. Variable inflorescences, with bilateral flowers, often with large, colorful bracts and bracteoles; 5 connate sepals/5 connate petals, 4 didynamous stamens, with filaments adnate to corolla. Superior ovary, 2 fused carpels, with axile placentation. Fruit an explosively dehiscent capsule with a funicle that is modified into a retinacula (a hook-shaped stalk that flings seed out).
