Cerastium fontanum subsp. vulgare (Hartman) Greuter & Burdet  
Family: Caryophyllaceae
big chickweed
[Cerastium adsurgens Greene,  more]
Cerastium fontanum subsp. vulgare image
Max Licher  
Plants perennial (very rarely annual). Inflorescences usually eglandular, occasionally viscid and glandular. Petals equaling sepals. Capsules 9-13 mm. Seeds 0.4-0.9 mm; tubercles small. 2n = ca. 122-152, usually 144. Flowering throughout growing season. A common weed in grassy places: lawns, roadsides, pastures, open woodlands, wastelands; 0-3000 m; introduced; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; introduced worldwide. Small annual forms of subsp. vulgare can be difficult to separate from Cerastium pumilum. The latter has smaller capsules, narrower and sharply acute sepals, and short, glandular hairs on the sepals, bracts, and inflorescence.

Perennial herb 15 cm - 0.5 m tall Stem: upright from a decumbent base, branched at the base, softly hairy. Non-flowering shoots may be seen growing from the base. These short, branched shoots are often rooting at the nodes. Leaves: opposite, in distant pairs, stalkless, 1 - 2.5 cm long, 3 - 12 mm wide, elliptic to oblong egg-shaped with a blunt or somewhat pointed tip, densely long-hairy. The leaves of the sterile shoots are reverse lance-shaped to spatula-shaped. Inflorescence: a lax, branched cluster (cyme) of three to fifty flowers subtended by hairy, lance-shaped bracts. The upper part of the bracts often have narrow, scarious (dry, thin, and membranous) margins. Flowers: white. Stalk somewhat curved, 2 - 12 mm long, and densely hairy. Stamens ten, sometimes five. Styles five. Sepals: five, distinct, 4.5 - 7 mm long, egg- lance-shaped with a pointed tip, hairy. Petals: five, white, equaling the sepals, reverse lance-shaped, deeply two-lobed, clawed. Fruit: a dehiscent capsule (opening by ten upright, short teeth), 8 - 13 mm long, 2 - 3 mm wide, longer than the sepals, narrowly cylindrical, curved. Seeds numerous, reddish brown, egg- to kidney-shaped, dorsally grooved.

Similar species: Having some or all of the bracts with scarious margins (or at least the upper part of the bracts) helps to distinguish this species, Cerastium arvense, C. pumilum, and C. semidecandrum from most other Cerastium in the Chicago Region. Cerastium arvense differs by having petals that are usually more than 10 mm long. The annuals Cerastium pumilum and C. semidecandrum differ by having five stamens and no basal offshoots.

Flowering: late March to mid-November

Habitat and ecology: Introduced from Eurasia. Common in lawns.

Occurence in the Chicago region: non-native

Etymology: Cerastium comes from the Greek word keras, meaning horn, referring to the horn-like shape of the seed capsule. Fontanum means "growing in fast-running water, pertaining to springs or fountains." Vulgare means common.

Author: The Morton Arboretum

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