Annual, erect herb, usually 10–20 cm tall, sometimes reaching 50 cm, with simple or sparsely branched stems. Leaves are subsessile, linear to linear-lanceolate, entire, acute or obtuse, up to 35 mm long and 1–6 mm wide. Calyx is unequally and deeply 5-lobed. Corolla is pink to lilac-tinged outside, small, as long as or shorter than the calyx lobes and up to 10 mm long. Flowers have two pairs of unequal-length, included stamens. Fruits are small, ovoid capsules, 8–10 mm long, densely glandular-pubescent.