Perianth white with greenish to purplish veins. 2n = 24, 36, 48.

Flowering summer (Jun--Sep). Gravelly to rocky slopes and cliff faces or rock crevices, grassy tundra; 400--4400 m; B.C., N.W.T., Yukon; Alaska, Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.; Eurasia.

Variety serotina, the typical, arctic-alpine variety (T. Irmisch 1863; B. Jones and C. Gliddon 1999), is wide-ranging throughout the Northern Hemisphere (N. Woodhead 1951).