Herbs. Stems erect or creeping, 4-sided. Leaves petiolate; leaf blade papery to membranous, secondary veins 1 or 2 on each side of midvein, tertiary veins parallel, margin usually serrulate. Inflorescences terminal cymes, nearly capitate, 3-5-flowered, base 2-bracteate; bracts foliaceous. Pedicel short, 4-sided, usually narrowly winged. Hypanthium cupular to cupular-funnelform, 4-sided, usually winged on angles. Calyx lobes 4, apex usually truncate but tip armed pubescent or a fimbriate membranous disk. Petals 4, pink to purplish red, usually oblique, apex apiculate. Stamens 8, equal in size; anthers obcordate or obcordate-elliptic, dehiscience poricidal; connective base usually decurrent forming a curved spur or bulge. Ovary inferior, 4-celled, apex with a membranous crown. Capsule cup-shaped, 4-sided, 4-poricidal, crown usually exserted from hypanthium. Seeds small, numerous, long obovate, densely papillose tuberculate.
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