Annual with slender, branching taproot, minutely scabrous, often glandular-hairy above. Stems diffusely branched, lax or erect, 2–30 cm long. Basal leaves with petioles 1–2 mm long, cauline leaves sessile; lamina 1-veined, ciliate, 2–5 mm long, 2–2.5 mm wide. Inflorescence usually diffuse; bracts herbaceous. Flowers 3–5 mm diam.; pedicels 2–6 mm long, minutely scabrous, often glandular, more or less curved in fruit; calyx scabrous, sparsely glandular-puberulent, sepals lanceolate, acuminate, 3-veined, the inner with scarious margin, 2–3 mm long; petals white, ovate, half length of sepals. Capsule more or less conical above, thin-walled, 3–4 mm long, 1.2–1.4 mm diam; seeds black or dark red, more or less sharply tuberculate, 0.3–0.4 mm long. Flowers Oct.–Feb.