Approximately 120 species mainly of small perennials plus a few annuals from the arctic zone, south to the mountains of the temperate region including Mexico, also one species in Chile. They are allied to Arenaria, with awl-shaped to filiform leaves (generally evergreen in the perennials), arranged in tufts, hummocks or mats. The five-petalled flowers, mainly white, usually (but not invariably) open out flat and are carried singly or in small cymes or umbels.

Uses

Suitable for the rock garden, especially on rock ledges and "in crevices, scree, raised bed and in the alpine house. The species described are grown mainly for their hummock and cushion shapes, but some are also modestly pleasing in bloom. Well drained soil and a sunny site are essential, most appreciating some lime. Propagation by cuttings of tufted shoots from the perimeter of a plant in late summer, and seed sown in autumn or as soon afterwards as possible, in a cold frame.