Herb, annual, with slender tap root, usually glabrous. Stems procumbent to erect, sometimes densely tufted, with or without basal rosette leaves, 2–10 cm long. Leaves rather fleshy, linear, obtuse or acute, often mucronulate, 3–15 mm long, 0.5–1 mm wide, rarely ciliate. Flowers 4-merous, c. 4 mm diam.; pedicels ± erect, 2–20 mm long, glabrous. Calyx glabrous. Sepals ovate, 2–3 mm long, hooded, obtuse, often with purplish margins, suberect in fruit. Petals minute or absent. Stamens 4. Styles 4. Capsule ovoid, ± equalling sepals, c. 2.5 mm long. Seeds obliquely reniform, 0.3–0.5 mm wide, brown, ± grooved dorsally, tuberculate.