Herbs, annual, mat-forming, glabrous. Roots fibrous. Stems prostrate. Leaves cauline, opposite, those of each pair unequal; stipules sheathing stem, attached to proximal petiole margins, scarious, fringed; blade flat, elliptical to obovate, smooth, tapered to base, margins entire. Inflorescences axillary, flowers solitary; bracts foliaceous; bracteoles scarious, fringed. Flowers inconspicuous, 2-3 mm diam.; calyx campanulate; calyx lobes 4-5, unequal; petals and petaloid staminodia absent; stamens (1-)3, alternating with calyx lobes; pistil usually 2-carpellate; ovary superior, 1-loculed, ovoid to globose; placentation free-central; styles and stigmas usually 2. Fruits capsules, dehiscence circumscissile. Seeds ca. 150; arils persistent on placentas, slender.