Perennial herbs and subshrubs. Leaves opposite, decussate. Cystoliths numerous, often conspicuous. Inflorescences of axillary or terminal, unilateral, fasciculate to spiciform cymes often aggregated into dense compound inflorescences; rarely a dichasial cyme or flowers solitary. Calyx deeply and unequally 5-lobed; posterior lobe broader than other lobes, anterior pair sometimes partly fused. Corolla 2-lipped; tube cylindric below, campanulate in throat; upper lip hooded; apex 2-lobed; lower lip with 3-lobed apex; palate upraised with a central furrow. Stamens 4, fertile, didynamous; anterior pair longer, 2-thecous, posterior pair shorter, 1-thecous or 2-thecous. Ovary 2-locular with 1-2 ovules per loculus. Capsule flattened, 2-seeded. Seeds held on retinacula, clothed with hygroscopic hairs. Worldwide: c. 100 species in the tropics and subtropics Zambia: 15 taxa. |
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