Annual, similar to Arenaria serpyllifolia but branches and stems more slender, often scabrid on one side; leaves obovate or orbicular, subpetiolate, apiculate. Bracts lanceolate; inflorescence dichasial, few-flowered; sepals lanceolate, acuminate to acute, 1-nerved; capsule usually as long as the sepals; seeds without prominent tubercles.