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DescriptionAnnual or perennial herbs. Leaves opposite. Inflorescences ± capitate to spicate, terminal on stems and branches. Modified sterile flowers 0; all flowers bisexual. Bracts persistent. Perianth segments 4-5, glabrous, 1-3-nerved. Stamens 4-5, alternating with distinct pseudostaminodes. Ovary with 1 pendulous ovule. Fruit a thin-walled capsule, splitting irregularly.