Family: Caryophyllaceae

This small genus of ten species of mostly alpine, cushion-forming plants are found worldwide. They make interesting additions to alpine or rockery gardens and attractive groundcovers. They can be grown between paving slabs or stories.

Species

S. biflorus, knawel or green rocks, a native of eastern Australia and New Zealand, forms a rounded cushion of bright green, moss-like foliage, spreading to about 35 cm (14 in). Tiny, bright green flowers appear in spring. This perennial plant is suitable for rockeries or as groundcover, with an attractive appearance whether massed or as a feature plant.

S. brockiei is an open, tufted perennial from New Zealand, with tiny, narrow, soft leaves and pairs of minute, stalkless flowers without petals.

S. pungens, from South Australia, is a cushion-forming plant, spreading to about 40 cm (16 in), with slender, stiff leaves, 1 cm (½ in) long, and white flowers held amongst the foliage.

S. uniflorus, from New Zealand, is a compact, tufted perennial which grows to 20 cm (8 in) across. The tiny, leathery leaves are quite rigid and pressed close to the stems, and the solitary flowers are stalkless.

Cultivation

S. biflorus is probably the best known species and this and others will need seeking out from alpine specialists. These plants need sharply drained, sandy soil which is able to retain adequate moisture. Make sure the soil is free from perennial weeds before planting, as the weeds not only spoil the appearance of these plants, but may in fact smother them. Propagate from seed, or by division of the plants in either spring or autumn.

Climate

Zone 7.