Arenaria ciliata Linnaeus subsp. pseudofrigida Ostenfeld & Dahl, Nyt Mag. Naturvidensk. 55: 217. 1918; A. ciliata var. pseudofrigida (Ostenfeld & Dahl) B. Boivin

Plants perennial, forming cush-ions or mats.  Taproots filiform to somewhat thickened.  Stems 20-40+, procumbent, green, 3-14 cm; internodes terete to angular, 1/ 2-1+ times as long as leaves, shiny, pubescent in lines or throughout, hairs retrorsely curved. Leaves connate basally, with scarious sheath 0.2-0.3 mm, sessile; blade 1-veined (prominent proximally), oblanceolate to spatulate, 2-6 × 0.8-1.8 mm, succulent, margins thickened, minutely scarious-granular, ± shiny, ciliate in proximal 2, apex ± obtuse, sometimes pustulate, glabrous; axillary leaf clusters absent. Inflorescences terminal or axillary, open, leafy, 1-4-flowered cymes in distal leaf axils. Pedicels erect or nodding in fruit, 2-12 mm, retrorsely pubescent. Flowers: sepals green or distally purple, 3-veined (2 lateral veins 2 times as long as midvein), sometimes keeled, narrowly lanceolate (herbaceous portion narrowly lanceolate), 3-4 mm, to ca. 5 mm in fruit, apex ± acute, not pustulate, glabrous or sparsely stipitate-glandular; petals obovate, 5-8 mm, 1 3-2 times as long as sepals, apex acute to rounded. Capsules tightly enclosed by calyx, narrowly ellipsoid to cylindric, 3-5 mm, ca. equaling sepals. Seeds 15-20, black to reddish brown, reniform, compressed, 0.8-0.9 mm, shiny, low-tuberculate. 2n = 40.

Flowering spring-summer. Open, dry to slightly moist sand or gravel; 0-50 m; Greenland; Europe.

We follow B. Jonsell (2001) in treating Arenaria pseudofrigida as one of several arctic species that formerly were included in A. ciliata Linnaeus, a species now considered restricted to alpine regions of central Europe.