Plants perennial, creeping, rhi-zomatous. Stems decumbent and ascending, branched, smoothly 4-angled, 10-40 cm, glabrous. Leaves sessile; blade narrowly elliptic, elliptic-lanceolate, or oblanceolate, 0.5-2(-3) cm × 2-10(-13) mm, base cuneate, margins thin with reticulate venation, entire, apex acute, glabrous, slightly ciliate basally. Inflorescences axillary with 1-5-flowered cymes in mid and distal axils of foliage leaves; bracts lanceolate, ca. 1 mm, scarious with green midrib. Pedicels 5-30 mm, glabrous. Flowers ca. 6 mm diam.; sepals 5, 3-veined, lanceolate-triangular, 2.5-3.5 mm, margins scarious, apex acute, glabrous; petals 5, 1.5-3 mm, shorter than (rarely equaling) sepals, blade apex 2-fid almost to base, with widely divergent lobes; stamens 10; styles 3, ca. 1 mm. Capsules green, ovoid, 2.5-3.5 mm, equaling sepals, apex broadly acute; carpophore absent. Seeds pale reddish brown, ± reniform, 0.3-0.4 mm diam., with small tubercles. 2n = 24. Flowering spring-early summer. Streamsides, flushes, wet tracks, ditches; 0-300 m; St. Pierre and Miquelon; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., P.E.I., Que.; Del., D.C., Ga., La., Maine, Md., Mass., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., Tenn., Vt., Wash., W.Va.; Europe; introduced in South America (Chile). Stellaria alsine is presumed to be native in eastern North America but has been introduced elsewhere in North America and Chile.
Slender perennial with decumbent or ascending, glabrous, angled stems, often rooting at the nodes; lvs mostly 1.5-3 cm נ1.5-6(-10) mm, elliptic to oblanceolate or linear-oblong, acute, the upper sessile, the lower petiolate, glabrous except for the basally ciliate margins; cymes axillary, few-fld; bracts tiny, narrowly lanceolate, scarious; pedicels slender, clavate at the summit; fls with a definite short hypanthium; sep 2.5-3.5 mm, narrowly lanceolate, acute; pet shorter than the sep; fr ovoid, ±exceeding the sep; seeds 0.5-0.7 mm, obovate, somewhat caudate, strongly papillate or rugose-papillate; 2n=24, 26. Cold marshes, streams, and springs; Nf. and Que. to Md. and W.Va., and occasionally elsewhere in our range; widespread in Eurasia and perhaps only intr. with us, but appearing native. May-Aug. (Alsine uliginosa)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.