Arenaria Linnaeus subgen. Spergularia Persoon, Syn. Pl. 1: 504. 1805; Buda Adanson, nom. rej.; Tissa Adanson, nom. rej.

Herbs annual or perennial. Stems erect, decumbent, or procumbent, dilated at nodes, somewhat flattened. Leaves decussate, linear; stipules pale, scarious, connate around nodes, forming ± triangular structures on either side of stem; leaf fascicles (short, leafy lateral branches) when present borne on only one side at each node. Inflorescence of racemose cymes; bracts immediately subtending calyx absent. Sepals 5, free, green, margin scarious. Petals 5, white or pink, entire. Stamens 2--5 or 10. Ovary 1-loculed; ovules numerous; styles 3. Capsule ovoid, opening by 3 valves. Seeds numerous, flat, winged or not; embryo curved.

About 25 species: N temperate regions, mostly halophytes; four species in China.

(Authors: Lu Dequan; Richard K. Rabeler)