Plants perennial. Rhizomes form-ing extensive network. Stems ascending to erect, simple or branched, ± angled or grooved, 2-18 cm, hairs minute, spreading, peglike. Leaves sessile or subses-sile; petiole 0.1-1 mm; blade 1-3-veined, lanceolate to elliptic, (8-)15-50(-70) × 2-9 mm, margins smooth to minutely granular, often ciliate in proximal 1/ 2, apex acute. Inflorescences 1-5-flowered; bracts 1-4 mm, margins broadly scarious. Pedicels ascending to erect, sometimes divergent in fruit, 2-15 mm. Flowers: sepals 5, midrib ± keeled, ovate, herbaceous portion lanceolate, (2.8-)3-6 mm, apex acute to acuminate; petals 5, 2-6 mm, 3/ 1/ 2 times as long as sepals. Capsules ovoid, 5 mm, ± equaling sepals. Seeds ovoid, 1.5-2.2 mm, tuberculate; tubercles minute, low, rounded. 2n = 48.
Flowering late spring-summer. Moist, shaded slopes, rocky ridges, ultramafic outcrops and summits, shores; 200-3400 m.; B.C., Man., Nfld. and Labr. (Labr.), N.W.T., Ont., Que., Sask.; Calif., Colo., Conn., Idaho, Mass., Mich., Mont., N.Mex., Ore., Utah, Vt., Wash., Wis.; Asia.
Much like no. 2 [Arenaria lateriflora L.] ; lvs mostly 2-5 cm נ3-8 mm, lanceolate, elliptic, or oblanceolate, obtusish to more often acute or acuminate; sep 3-6 mm, broadly lanceolate, acutish to acuminate, from a little shorter to often evidently longer than the pet; fr shorter than the sep, globose-oblong, sometimes dehiscing only to the middle; seed 1.5 mm, with a conspicuous strophiole; 2n=48. Woods, stony slopes, and plains; Lab. and Que. to Vt., Mass., n. Mich., and Wis.; and in the w. cordillera. May-Aug. (Moehringia m.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.