Although a proposal to reject Spergularia media as a confused name (J. Lambinon 1981) was rejected, some authors still favor that argument, preferring to use the name S. maritima for this species.
Spergularia media is one of the 'highway halophytes' (A. A. Reznicek 1980) that have spread along highways that are heavily salted during the winter, where saline areas have been created. Spergularia distribution has been investigated in Ohio (A. W. Cusick 1983), where such records were first noted in the early 1970s.
Annual or perennial herb with a taproot 15 - 40 cm tall Stem: prostrate or upright, much-branched, sometimes sparsely glandular-hairy above. Leaves: opposite, stalkless, 1 - 5 cm long, 0.8 - 2 mm wide, linear, sometimes shortly bristle-tipped, one-veined, fleshy. Stipules two per node, fused at the base, 1.5 - 6 mm long, triangular, scarious (dry, thin, and membranous). Inflorescence: a terminal, widely branched cluster (cyme) of flowers, glandular-hairy, subtended by reduced bracts. Flowers: white or pink. Stamens seven to ten. Styles three. Sepals: five, green, 3 - 7 mm long, 1.5 - 2 mm wide, narrowly egg-shaped, scarious-margined (dry, thin, and membranous). Petals: five, white or pink, shorter than sepals, oblong. Fruit: a dehiscent capsule, opening by three spreading valves, 5 - 8 mm long, egg-shaped. Seeds many, dark brown, about 1 mm long, orbicular, with a membranous wing.
Similar species: The similar Spergularia marina differs by having less stamens per flower (two to five). Spergularia rubra is also similar but has wingless seeds and leaves that are scarcely fleshy.
Flowering: June to early October
Habitat and ecology: Introduced from Europe. Frequent in the western sector of the Chicago Region, typically along roads and highways where the salinity is high from winter salting.
Occurence in the Chicago region: non-native
Etymology: Spergularia refers to the genus Spergula (which comes from the Latin word spargo, meaning sow or scatter, referring to the discharge of seeds). The Latin -aria means "pertaining to." Media means middle or average.
Erect or prostrate, much-branched annual or perennial to 40 cm, glabrous or sparsely glandular-puberulent above; lvs 1-5 cm נ0.8-2 mm, with short or no mucro; stipules deltoid, 1.5-6 mm; sep narrowly ovate, 3-6 mm; pet white (seldom pink), shorter than the sep; stamens (7-)9-10; fr 5-8 mm; seed 0.6-1.1 mm, smooth or minutely sculptured, the marginal wings 0.1-0.4 mm wide, entire or erose; 2n=18, 36. Native of Europe, intr. in salt flats and marshes in coastal and c. N.Y., and along salted highways in O., Mich., and Ill.; to be expected elsewhere in our range. (S. maritima)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.