Ross's sandwort

Arenaria rossii R. Brown ex Richardson in J. Franklin et al., Narr. Journey Polar Sea, 738. 1823; Alsinanthe rossii (R. Brown ex Richardson) Á. Löve & D. Löve; Alsinopsis rossii (R. Brown ex Richardson) Rydberg; Arenaria rossii var. apetala Maguire; Minuartia orthotrichoides Schischkin; M. rolfii Nannfeldt; M. rossii var. orthotrichoides (Schischkin) Hultén

Plants perennial, densely pulvinate to loosely cespitose. Taproots stout, woody. Stems ascending to spreading, green or often purple, 1-3 cm, glabrous, internodes of flowering stems 0.2-1 times as long as leaves. Leaves overlapping, ± tightly (vegetative), ± evenly spaced proximally (cauline), connate-perfoliate proximally, with tight, herbaceous sheath 0.2-0.3 mm; blade upwardly curved, green or often purple, keeled, prominently 1-veined abaxially, subulate, 3-angled, 1-4 × 0.5-0.7 mm, flexuous, margins rounded, herbaceous, smooth, apex green to purple, rounded, navicular, shiny, glabrous; axillary leaves well developed. Inflorescences solitary flowers, axillary or terminal (rarely present); bracts absent. Pedicels 0.1-2 cm, glabrous. Flowers: hypanthium disc-shaped; sepals 1-veined, oblong-ovate (herbaceous portion usually purple, oblong-ovate), 1.5-2.5 mm, not enlarging in fruit, apex often purple, obtuse to acuminate, navicular, not hooded, glabrous; petals obovate to spatulate, 1.5-2 times as long as sepals, apex obtuse, entire. Capsules on stipe ca. 0.1-0.2 mm, spheric, 1.5-2.5 mm, equaling sepals. Seeds brown, suborbic-ulate, compression unknown, ca. 0.6 mm, obscurely reticulate. 2n = 58 (Russia), 60.

Flowering spring-summer. Wet, turfy, gravelly, or sandy calcareous barrens, high arctic, alpine tundra, heathlands; 0-500 m; Greenland; N.W.T., Nunavut, Yukon; Alaska; Europe (Spitzbergen); Asia (Russian Far East).

Minuartia rossii is the northernmost member of the M. rossii complex (S. J. Wolf et al. 1979; B. Maguire 1958), a pulvinate species of moist arctic areas. While specimens occasionally have many flowers, some specimens have few if any, instead reproducing via small axillary fascicles of leaves or short shoots in the upper leaf axils (see also Ö. Nilsson 2001).