6. Sagina caespitosa (J. Vahl) Lange in H. J. Rink, Grønland. 2: 133. 1857.
Arenaria caespitosa J. Vahl in G. C. Oeder et al., Fl. Dan. 13(39): 4. 1840; Sagina nivalis (Lindblom) Fries var. caespitosa (J. Vahl) B. Boivin; Spergella caespitosa (J. Vahl) Á. Löve & D. Löve
Plants perennial, cespitose, forming small mats or cushions, glandular-pubescent or glabrous. Stems ascending to spreading, frequently purple tinged, many-branched, not filiform. Leaves: axillary fascicles absent; basal not in primary rosettes, secondary rosettes usually present, blade linear to linear-subulate, 2-13 mm, not fleshy, apex apiculate to acute, glabrous; cauline connate basally, forming shallow, often purplish, scarious cup, blade with frequently conspicuous midvein, subulate, 3-9(-12) mm, becoming shorter toward apex, not fleshy, apex apiculate to acute, glabrous. Pedicels filiform, glandular-pubescent, rarely glabrous. Flowers terminal, 5-merous or 4- and 5-merous; calyx base glandular-pubescent or glabrous; sepals broadly ovate to lanceolate, 2-2.5 mm, hyaline margins usually purple tinged, at least at apex, apex obtuse to somewhat acute, glandular-pubescent or glabrous, remaining appressed after capsule dehiscence; petals elliptic to narrowly obovate, 2.5-3 mm, longer than or seldom equaling sepals; stamens 8 or 10. Capsules 3-3.5 mm, exceeding 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.
Flowering mid-late summer. Wet sands and gravels of shorelines and stream margins, wet mossy places, dry rocky barrens, gravelly hillocks; 0-1300 m; Greenland; Man., Nfld. and Labr., Nunavut, Que.; arctic Europe.