Prostrate annual herb with a somewhat swollen tap-root; stems often reddish and sometimes rooting at the nodes, sometimes reaching 25 cm long and c. 1 cm in diam. Leaves opposite; lamina fleshy, up to 10 × 4 mm, but often much less and frequently somewhat shrunk in dried specimens, elliptic, lanceolate, elliptic-oblong or rarely cordate-ovate, apex acute or obtuse, both surfaces more or less flattened; petiole c. 1 mm. long; stipular hairs whitish, numerous, 3–5 mm long. Flowers 1–4 at the ends of the branches, surrounded by 4 leaves often somewhat larger than the cauline ones and by numerous hairs c. 4 mm long. Sepals 2–4 × 1·5–3·5 mm ± triangular, obtuse, united at the base. Petals 4 (5), yellow or orange or very rarely pink or purplish, almost free, c. 5 × 3 mm, elliptic to ovate. Stamens 8–12. Ovary conical-ovoid; style c. 5 mm long, thickened at the apex and with 4 spreading stigmas. Capsule conical-ovoid, dehiscing horizontally c. 1/3 of the way up. Seeds many, c. 1 mm in diameter, greyish, reniform, verrucose with blunt tubercles.

The stamen number and flower size of P. quadrifida however may be variable