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DescriptionHerbs, erect, creeping or climbing. Leaves opposite, sometimes cordate or hastate at base. Flowers axillary. Bracts 2, large, elliptic or ovate, enveloping the small calyx. Calyx usually of 10-18 linear teeth, rarely a small saucer-shaped body. Stamens 4, didynamous, 2-thecous; anthers opening by longitudinal slits. Retinacula 0. Ovary 2-locular, with 2 ovules in each loculus. Fruit a spherical beaked capsule. Distinguished by the large bracts, the calyx with its numerous lobes, the method of anther dehiscence and the beaked fruit.See Pseudocalyx for the differences with that genus.