Plant: annual; straight often stout hairs; stems 4-angled, decumbent, often much branched from the base, frequently rooting at nodes, 7-36 cm long Leaves: including leaf-like stipules appear whorled, 5-6 per node, 4-13 mm long, lanceolate-oblanceolate; apices acute or pungent; margins with white callous, with apically directed short stoutish hairs INFLORESCENCE: heads, solitary in upper axils on slender 3-25 mm long peduncles, the involucre commonly of 8 leaf-like lobes united 1/8-1/4 their length Flowers: 2-3 per head, sub-sessile, ca. 4 mm long, scarcely exserted from deeply divided involucre; calyx of 6 persistent teeth which crown the fruit; corolla pink or lavender, salverform, the tube slender, the limb usually 4-lobed, the lobes ovate, spreading; stamens included; pistil slightly exserted; mature carpels softly pubescent with appressed hairs; style filiform, 2-cleft Fruit: dry, didymous, separating into 2 indehiscent 1-seeded carpels Misc: Naturalized in lawns; 300-750 m (1000-2500 ft); Apr-May REFERENCES: Terrell, Edward E. 1995 Rubiaceae. Houstonia. J. Ariz. - Nev. Acad. Sci. 29(l): 36.
Annual herb to 40 cm tall Leaves: mostly in whorls of six, stalkless, 0.5 - 2 cm long, 3 - 4 mm wide, linear to narrowly elliptic with a sharply pointed tip, hairy. Inflorescence: a cluster of three or more flowers surrounded by about eight basally fused, narrowly lance-shaped leaves. Flowers: blue or pink, 4 - 5 mm long, funnel-shaped, tube slender, with four triangular, spreading lobes. Stamens four, about equaling corolla lobes. Anthers purplish. Styles two, short. Fruit: dry, indehiscent, 2 - 7 mm long, reverse egg-shaped, paired, rough, two-ribbed longitudinally, crowned by persistent sepals, two-seeded. Stems: multiple from base, prostrate to ascending, square, diffusely branched, more or less roughly hairy (mainly below).
Similar species: At first glance, Sherardia arvensis looks like a Galium; however, the blue or pink flowers surrounded by a group of basally fused leaves will distinguish it immediately.
Flowering: July to late August
Habitat and ecology: Introduced from Eurasia. Relatively frequent south of the Ohio River, but increasingly rare northward. May be found growing in disturbed areas. There are several well-established colonies growing as a lawn weed at the entrance of a cemetery (the North Shore Memory Gardens) in Berrien County, Michigan.
Occurence in the Chicago region: non-native
Etymology: Sherardia is named after Dr. William Sherard (1659-1728), an English botanist. Arvensis means "of farmed or cultivated fields."
Author: The Morton Arboretum
Fls 4(-6)-merous; sep erect; cor funnelform with slender tube; stamens about equaling the cor-lobes; ovary bilocular, with a single axile ovule in each locule; style unequally bifid; fr dry, longitudinally 2-ribbed, crowned by the persistent sep; herbs with whorled lvs and small fls in terminal heads, surrounded by an involucre of lanceolate, basally connate lvs. Monospecific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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Citation: The vPlants Project. vPlants: A Virtual Herbarium of the Chicago Region. http://www.vplants.org
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