Annual or perennial, c. 20 cm, erect, or prostrate herb with upright branches, rooting at nodes. Root c. 10 cm long. Stem and branches cylindrical, smooth, succulent, glabrous, purplish green. Leaves alternate or irregularly scattered, subsessile, semi-cylindrical or subterete, linear-oblong, acute, 6-30 mm long, 2-3 mm broad, fleshy, glabrous, entire; stipular hairs few in axils, 2-8 mm long, white. Inflorescence 1-3-(or rarely 4)-flowered cymose sessile clusters sub-tended by a dense growth of hairs and 5-8 leaved involucre. Flowers large, showy, sessile, yellow, pink or scarlet, 2-5 cm across. Sepals slightly unequal, united at the base into a short tube, broad ovate, 6-7 mm long, 3.5-4.5 mm broad, somewhat hooded at the apex, acute. Petals 5 or multiples of 5, united at the base, obovate, pale brown or yellow spotted at the base, 16-18 mm long, 12-14 mm wide, emarginate. Stamens numerous, united at the base; filaments unequal, 4-5 mm long, scarlet-purple in colour. Carpels 5, syncarpous; ovary ovoid; style 6-7 mm long, 5-fid; stigmas 5, linear, 2-3 mm long, recurved. Capsule oblong, obtuse, c. 5 mm long, c. 3 mm in diam. Seeds minute, compressed, metallic grey or greyish-black.

Fl. Per. Summer.

Type: Argentine Between Rio del Saladillo or western boundary of the Pampas, and the foot of the mountain near Mendoza, Dr. Gillies (K).

Distribution: A native of South America, commonly grown in gardens.

Rose moss is cultivated as an ornamental plant for its handsome single and full double flowers of various colours. It is very good for growing in dry rockeries and occasionally becomes established on roadsides and waste places.