Slender, 8-25 cm annual , with habit of Arenaria. Leaves opposite, oblong-elliptical, obtuse, 5-12 mm, the lower ones broadly obovate, smaller and crowded. Cyme lax. Sepals ovate elliptical, shortly acuminate, glandular-margined, 2-2.5 mm, as long as capsule. Petals white, 4-5 mm. Fl. 6-8. Stream-sides, flushes, moist banks, Rhododendron scrub, s.l.-2500 m.
Throughout most of Europe, N. W. Africa, Caucasia, N. & W. Iran. Euro-Sib. element.