About 150 species of annuals and perennials, less commonly biennials and subshrubs from the arctic and northern temperate zones, especially on mountains. They are mainly small tufted plants with opposite pairs of filiform to narrowly lanceolate leaves (rarely ovate) and five- occasionally four-petalled mainly white (sometimes pink to purple) flowers, either solitary or in cymes.
Many of the cushion to mat-forming species are choice plants for the raised bed, scree or alpine house. Others are good general purpose plants which no rock garden should be without, e.g. A. balearica and A. montana. Well drained soil and a sunny site suits most species. Other requirements are noted in the species' descriptions below. Propagation by seed sown when ripe or as soon as possible afterwards, kept in a cold frame or outside. Some species can be divided in early spring or after flowering; cuttings can be taken in spring or late summer.