Northern starwort

Arenaria calycantha Ledebour, Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 5: 534. 1815; Alsine calycantha (Ledebour) Rydberg; A. simcoei Howell; Stellaria borealis Bigelow var. simcoei (Howell) Fernald; S. calycantha var. simcoei (Howell) Fernald; S. simcoei (Howell) C. L. Hitchcock

Plants perennial, forming clumps, from slender rhizomes. Stems erect or trailing, branched, square, weak, to 25(-35) cm, glabrous or pilose, never papillate. Leaves sessile or subsessile; blade ovate to elliptic, rarely oblong, widest proximal to middle, 5-25 mm, thin, base round, margins entire, apex acute, glabrous or rarely ciliate. Inflorescences terminal, 1-5-flowered cymes; bracts foliaceous. Pedicels ascending, not reflexed, 5-25(-50) mm, glabrous. Flowers 3-5 mm; sepals 5, obscurely veined, ovate, 2-2.5 mm (rarely 3.5 in fruit), margins broad, scarious, apex broadly acute, glabrous; petals absent or 1-5, 1-1.5 mm, shorter than sepals, blade apex deeply lobed; stamens 5; styles 3, usually curved, 0.4-0.9 mm. Capsules green, semitransparent, globose to broadly ovoid, 3-5 mm, to 1.5 times as long as broad, longer than sepals, apex obtuse, opening by 3 valves; carpophore absent. Seeds brown, ovate, 0.5-0.9 mm, smooth or shallowly tuberculate. 2n = 26.

Flowering summer. Alpine slopes, meadows, shores of lakes and streams; 0-3700 m; Alta., B.C., N.W.T., Yukon; Alaska, Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.; Asia (Russian Far East).