Perennial, prostrate-erect herbs or undershrubs. Leaves sessile or petiolate, opposite or pseudo-whorled, simple, entire or spinescent toothed. Flowers in axillary clusters or strobilate spikes or solitary; bracts 4-ranked, closely imbricated, spinose, persistent; bracteole lanceolate to spathulate, hairy. Calyx unequally deeply 4-lobed, 2 inner lobes shorter than the 2 outer, imbricate, persistent. Corolla tube shorter than the limb, indurate, limb not 2-lipped, upper lip absent or rudimentary, lower lip almost flat, usually 3-lobed, imbricate. Stamens 4, didynamous, all fertile, exserted, filaments inserted at base of corolla tube, thickened, anthers monothecous with white hairs, the other cell sterile or absent. Ovary bilocular, 4 or 2-ovuled; style bifid. Capsule oblong or ellipsoid, compressed, 2 or 4-seeded. Seeds flattened, beset with coiled hygroscopic hair bundles; retinacula stiff.