57. Silene sorensenis (B. Boivin) Bocquet, Candollea. 22: 21. 1967.
Lychnis sorensenis B. Boivin, Canad. Field-Naturalist 65: 6. 1951; Agrostemma triflorum (R. Brown ex Sommerfelt) G. Don; Lychnis affinis J. Vahl ex Fries var. triflora (R. Brown ex Sommerfelt) Hart; L. triflora R. Brown ex Sommerfelt, not Silene triflora Bornmüller; Melandrium triflorum (R. Brown ex Sommerfelt) J. Vahl; Wahlbergella triflora (R. Brown ex Sommerfelt) Fries
Plants perennial, cespitose; taproot long, stout; caudex usually branched. Stems simple below flowering region, stout, 5-30 cm, pubescent, viscid-glandular, densely so distally, ciliate at nodes, hairs with purple septa. Leaves: basal petiolate, tufted, petiole to length of blade, broad, blade oblanceolate, 1-8 cm × 2-8 mm, fleshy, base blunt, tapering into petiole, margins ciliate, apex ± acute, glabrous (rarely pubescent) on both surfaces; cauline in 1-2 pairs, sessile, connate proximally, blade narrowly oblong-lanceolate, 5-30 × 1.5-5 mm, apex purple-tipped, ± acute, pubescence as in basal leaves. Inflorescences cymose, single, terminal, congested, 1-3-flowered, bracteate, rarely with 1 or 2 flowers in axil of mid-stem leaves (occasionally branched with 2 or 3 erect, elongate branches), densely woolly with purple septate hairs of various lengths, longest equaling pedicel diam.; bracts leaflike, lanceolate, 4-10 mm. Pedicels stout, usually much shorter than calyx, rarely to 2 times as long, or flowers sessile. Flowers: calyx broadly 10-veined, ovate-campanulate, ca. 10 × 6 mm in flower, enlarging to 15 × 10 mm in fruit, base round, narrowed to ca. 1/ 2 its diam. at mouth, margins dentate, teeth purple, ovate-obtuse, ca. 2 mm, pubescence densely glandular, viscid, partially obscuring the broad veins; corolla white to dingy pink, clawed, claw equaling calyx, limb obovate, 2-lobed, 3-5 mm, appendages 2, oblong, ca. 1 mm, margins crenulate; stamens equaling petals; styles 5, equaling petals. Capsules included in calyx, dehiscing by 5 teeth, often splitting into 10; carpophore 1-1.5 mm. Seeds brown, not winged, triangular-reniform, ca. 1 mm, spinose-papillate. 2n = 72.
Flowering summer. Arctic tundra in gravel and clay; 0-300 m; Greenland; N.W.T., Nunavut.
Silene sorensenis usually is readily separable from most other arctic silenes by the dense purplish pubescence that tends to obscure its calyx venation, the nonwinged seeds, and the congested flowers. Specimens of S. taimyrensis in the western arctic can resemble S. sorensenis but are distinguishable by their smaller seeds and calyx, more-slender stems, and hairs that are shorter than the diameter of the pedicel. Apparent hybrids with S. involucrata are occasionally encountered. A. Nygren (1951) considered S. sorensenis to be of amphidiploid origin involving S. uralensis and S. involucrata.