Annual, small, glandular herb; branches fascicled from the base; leaves sessile, opposite or in false whorls, linear, slender, spreading, grooved beneath; stipules small, scarious; flowers in terminal, peduncled, panicle or subumbellate cymes (rarely solitary); pedicels slender, pubescent, spreading or deflexed; sepals-5, ovate, obtuse, hairy, glandular, slightly shorter than petals, margins very narrow, membranous; petals-5, white, entire, obtuse; stamens 5+5, inserted on a perigynous disk, annular or divided into glands, anthers yellow; ovary 1-celled (rarely 3-celled), ovules many; styles 3 or 5, opposite the petals; capsules 5-valved, longer than sepals, subglobose, shining; seeds tubercled, black.