Perennial subshrubs, mat- or cushion-forming. Leaves cauline, sessile, imbricate; stipules reduced to a connate sheath. Flowers solitary, terminal; pedicels straight, rigid, becoming more or less woody. Perianth 4-merous; calyx foliaceous, calyx with 1 pair of sepals or lobes usually larger than other; sepals in 1 series and partly to largely united, or in 2 series of 2 decussate pairs; corolla white, lobes valvate or imbricate; stamens inserted at sinuses, anthers almost sessile, apiculate; ovary superior, placenta axile-apical, peltate, elongating in fruit, extending along the upper wall of the locule, ovules several, styles 2. Fruit capsular, persistent, woody, flattened in plane at 90° to septum, loculicidal; seeds several, ellipsoidal.
3, possibly 4, species in Australia and New Zealand; 2 species in Australia. All species are alpine plants from the herbfields above the tree line although S. montana also occurs at sea-level in Tasmania.