Plants loosely mat-forming, not stoloniferous, rhizomatous, from caudex. Leaves cauline, (not imbricate), opposite (distalmost alternate); petiole absent; blade oblanceolate to elliptic, unlobed, 5-9 mm, fleshy, margins entire, ciliate, with 1(-3) lime-secreting hydathodes, apex obtuse, surfaces glabrous. Inflorescences solitary flowers, sometimes 2-flowered cymes, ebracteate, 3-4 cm, glabrate. Flowers: sepals erect, ovate, margins ciliate, surfaces glabrous; petals salmon to flesh colored, sometimes red or orange, rarely yellow, sometimes violet tinged, not spotted, obovate to oblanceolate, 12-15 mm, longer than sepals; ovary to 1/4 inferior. 2n = 52.

Flowering summer. Arctic marshes, damp tundra, alluvial river beds, dessicated ponds, inland nunataks; 0-1200 m; Greenland.

Saxifraga nathorstii is known only from northeastern Greenland. T. W. Böcher (1941) showed cytologically that this species may be an allopolyploid that originated as a hybrid between S. oppositifolia and S. aizoides; morpho-logically, phenologically, and ecologically, it is intermediate between the two species (see also T. J. Sørensen 1933).