Fls 5-merous, perfect, irregular, solitary or in cymes. Calyx us. tubular, free or adnate to ovary; lobes us. valvate. Corolla obliquely ± 2-lipped, lobes imbricate. Stamens 4 or 2, with or without a staminode, epipetalous; anthers connate or connivent in pairs, 2-celled, dehiscing lengthwise; disk annular or of separate glands. Ovary superior to inferior, 1-loculed; placentae parietal, sts projecting so far inwards as to fuse incompletely; style 1, slender. Fr. us. capsular, seeds ∞. Herbs, shrubs, lianes, or trees with radical or opp., often anisophyllous, lvs. Some 85 genera and 1200 spp., mainly tropical and subtropical.