Shrubs or herbs. Stems usually 4-sided, narrowly winged when young, often subterete when older. Leaves petiolate; leaf blade membranous to papery, secondary veins 1 or 2 on each side of midvein, tertiary veins parallel, margin serrulate to subentire but sparsely setose ciliate. Inflorescences terminal or axillary, umbellate corymb, rarely umbellate; bracts often lanceolate to triangular-lanceolate. Pedicel 4-sided; bracteoles 2. Hypanthium campanulate, usually contracted at middle, 4-sided, 8-ribbed. Calyx lobes 4, often ovate, apex apiculate. Petals 4, red, purple, or sometimes pink, ovate to obovate, oblique. Stamens 8, whorls unequal in length; anthers lanceolate to long lanceolate, not tuberculate; connective not or minutely inflated at base, shortly spurred. Ovary inferior, 4-celled, apically denticulate. Style filiform; stigma apiculate. Capsule globose to ovoid-urceolate, 4-sided; hypanthium often glabrous. Seeds numerous, long cuneate to narrowly triangular, small, ribbed on angles, densely tuberculate.
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