Plants perennial, cespitose, forming low cushions, glabrous. Stems ascending or spreading, radiating from axils of basal rosette leaves, sometimes purple tinged, many-branched, slender. Leaves: axillary fascicles absent; basal in primary rosettes, secondary rosettes absent, blade subulate to linear, to 20(-30) mm, fleshy, apex apiculate, glabrous; cauline connate basally into shallow cup, blade often purplish, subulate to linear, 4-16 mm, becoming shorter toward stem apex, scarious, apex apiculate, glabrous. Pedicels filiform, glabrous. Flowers mostly terminal, 4-merous or 4- and 5-merous; calyx base glabrous; sepals frequently purplish, nearly orbiculate to elliptic, 1.5-2 mm, hyaline margins nearly always purple, sometimes only at apex, apex rounded, glabrous, remaining appressed following capsule dehiscence; petals narrowly elliptic, 1.5-2 mm, equaling to slightly shorter than sepals; stamens 8 or 10. Capsules 2-3 mm, usually shorter than sepals, dehiscing to base. Seeds brown, obliquely triangular with abaxial groove, 0.5 mm, lateral surfaces frequently with elongate ridges, abaxial surface appearing smooth to pebbled. 2n = 56, 88. Flowering mid-late summer. Sandy or gravelly beaches, coastal rocks, alluvial plains, fresh glacial moraines, low, swampy tundra, alpine areas; 0-2800 m; Greenland; Alta., B.C., Nfld. and Labr. (Labr.), N.W.T., Nunavut, Que., Yukon; Alaska, Mont.; arctic Eurasia.