Robust annual. Stems 10-30 cm, erect to ascending, branching from the base, white woolly at the base. Leaves opposite, or apparently whorled, 10-15 x 0.5-0.75 mm, linear to linear-subulate, 1-nerved, glabrous or nearly so when mature. Stipules c. 3 mm, lanceolate acuminate, ciliate. Flowers in compact, terminal cymes, with corymbose branching. Pedicels as long as or smaller than the sepals, woolly. Sepals 3-3.5 mm, lanceolate, acuminate, glabrous, entirely scarious silvery-white. Petals shorter than the sepals, emarginate. Capsule included in the sepals, dark brown. Valves with a narrow thickened yellow margin. Seeds small subtrigonous, smooth.