Herbs annual or perennial. Stems single or sparsely caespitose, prostrate to diffuse or erect. Leaf blade usually lanceolate to ovate, rarely linear or subulate, herbaceous, rarely leathery. Inflorescence various, terminal or axillary, sometimes reduced to 1--3 flowers. Petals white, often shorter than sepals. Sepals not incrassate or only slightly so at base.

McNeill (Notes Roy. Bot. Gard. Edinburgh 24: 79–155. 1962) subdivided Arenaria subgen. Arenaria into 11 sections, four of which occur in China: A. sect. Arenaria (species no. 1); A. sect. Rotundifoliae McNeill (loc. cit.: 113; species nos. 2 and 3); A. sect. Rariflorae F. N. Williams (Bull. Herb. Boissier 3: 602. 1895; species nos. 4 and 5); and A. sect. Compressae McNeill (loc. cit.: 118; species no. 6).

At least 106 species: centered in Europe but extending to Africa, Asia, and North America; six species (two endemic) in China.