Plants perennial, often mat-forming, glabrous. Stems as-cending or, more frequently, procumbent, rooting at nodes, giving rise to secondary tufts or rosettes, few- to many-branched, slender. Leaves: axillary fascicles often present on procumbent stems; basal frequently in primary rosettes in younger plants; blade linear, 8-17 mm, herbaceous, apex apiculate to somewhat aristate, glabrous; cauline not conspicuously connate basally, never forming an inflated cup, blade linear, 4-15 mm proximally, becoming shorter toward apex, 2.5-6 mm distally, sometimes slightly fleshy, apex apiculate to aristate, rarely with minute glandular cilia. Pedicels frequently recurved during capsule development, filiform, glabrous. Flowers axillary or terminal, 4-merous, occasionally 4- and 5-merous; calyx base glabrous; sepals elliptic to orbiculate, 1.5-(-2.5) mm, hyaline margins white, never purple tinged, apex obtuse to rounded, appressed during capsular development, divergent following dehiscence; petals (1-)4(-5), orbiculate to elliptic, 0.8-1(-1.5) mm, shorter than or equaling sepals, or sometimes absent; stamens 4 (8). Capsules (1.5-)2-2.5(-3) mm, slightly exceeding sepals, dehiscing to base. Seeds brown, obliquely triangular with distinct abaxial groove, (0.3-)0.4(-0.5) mm, smooth to pebbled. 2n = 22. Flowering late spring-early fall. Weedy, wet or damp, gravelly or sandy soils along roadsides, sidewalk cracks, margins of paths or lawns, pond and lake margins, coastal rocks and sands, sea cliffs; 0-3500 m; introduced; Greenland; St. Pierre and Miquelon; B.C., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que.; Alaska, Ark., Calif., Colo., Conn., Del., Idaho, Ill., Iowa, Maine, Md., Mass., Mich., Minn., Mont., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., Utah, Vt., Wash., W.Va., Wis.; Europe; introduced in Mexico (Chiapas, México), Central America (Costa Rica, Guatemala), s South America (Bolivia, s Argentina), Asia (w Siberia), Antarctica (sub-Antarctic Islands).
Perennial herb with a slender taproot, often mat-forming 2 - 10 cm tall Stem: slender, ascending to prostrate, few to much-branched, rooting at the nodes. Leaves: opposite (basal leaves often in a rosette), fused at the base (but not conspicuously), stalkless, 3 mm - 1.5 cm long, up to about 1 mm wide, reduced upwards down, linear with a pointed or bristly tip, one-veined. Flowers: one or few at branch tips, some axillary, white. Stamens as many as the sepals, opposite the sepals. Styles four or five, alternate with the sepals. Sepals: four or five, distinct, more or less spreading, green with white margins, 2 - 2.5 mm long, elliptic to orbicular with a blunt to rounded apex, scarious-margined (dry, thin, and membranous). Petals: four or five, sometimes none, white, about 1 mm long, shorter than or equal to the sepals, orbicular to elliptic. Fruit: a dehiscent capsule, 2 - 3 mm long, slightly exceeding the sepals. Seeds numerous, brown, tiny, more or less triangular, flattened, grooved.
Similar species: No information at this time.
Flowering: late June to mid-July
Habitat and ecology: Introduced from the southern states. Found on paths, moist lawns, in sidewalk cracks, and between paving bricks and patio blocks.
Occurence in the Chicago region: non-native
Etymology: Sagina means fodder or nourishment, coming from the belief that sheep fattened well in pastures where the plant grew. Procumbens means prostrate, referring to how the plant grows.
Glabrous, branching perennial, prostrate to ascending, the stems 2-10 cm; lvs linear-subulate, 3-10(-15) mm, to about 1 mm wide, mucronate or shortly aristate, sometimes minutely ciliate, frequently subtending short shoots or lf-fascicles; fls solitary or few at the tips of the stem and branches, or some of them on axillary pedicels, often nodding after anthesis, but finally erect; sep 4(5), 2-2.5 mm, spreading after maturity; pet shorter than the sep, or none; stamens as many as the sep; fr about equaling the sep, commonly 2-3 mm; seeds 0.3-0.5 mm, flattened, obliquely triangular, sulcate along the 2 dorsal angles, very finely roughened; 2n=22. Moist soil and rocky places, often a weed in paths or pavements; circumboreal, s. in Amer. to Md., Mich., and Kans. Summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.