Plants prostrate to ascending, 3-15 (-45) cm. Leaves not glaucous, in whorls of 3-8, basal rosette present, sometimes disappearing as plant matures; petiole 0.5-4 mm; blade linear to elliptic, obovate, or broadly spatulate, 5-40 × 0.5-15 mm, base cuneate, apex obtuse to rounded or acute. Inflorescences: flowers 2-6 in sessile, axillary umbels. Flowers: sepals green abaxially, white adaxially, oblong-elliptic, 1.5-2.5 × 0.5-1.2 mm, margins scarious; stamens 3[-4], alternate with carpels; pedicel erect-ascending at anthesis, erect to deflexed in fruit, 3-20 mm. Capsules ovoid-ellipsoid, 2.5-3.3 × 1.4-2.2 mm. Seeds 15-35, dark or reddish brown, with blackish, parallel, curved ridges on sides, or smooth, 0.5-0.6 × 0.4-0.5 mm. 2n = 64.

Flowering summer-early fall. Weedy in fields, gardens, roadsides, moist to dry soils, sand; 0-3000 m; B.C., Man., N.B., N.S., Ont., Que.; Ala., 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., Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; West Indies; Central America; South America; Eurasia; Africa.

Some authors consider Mollugo verticillata a native of the New World tropics that spread northward into subtropical and temperate regions (M. L. Fernald 1950; H. A. Gleason and A. Cronquist 1991). If so, the species apparently spread very rapidly, because herbarium specimens exist from Ohio in 1828, Michigan in 1837, and Maine in 1837. J. Chapman et al. (1974) presented archaeological evidence of pre-Columbian presence of M. verticillata at a site in Tennessee.

Morphology and anatomy of the species are well studied. T. Holm (1911) investigated anisophyly in Mollugo verticillata and stated that the leaves are not 'pseudo-verticillate,' as described by some earlier authors, but are truly opposite. M. A. Payne (1933, 1935) conducted morphologic and anatomic analyses of the leaf, stem, root, flower, and seed of the species. Pollen morphology was examined by N. Mitroiu (1971).

Several subspecific taxa have been described for Mollugo verticillata, but these are poorly understood; attempts to subdivide the species in North America for this treatment failed. The species is extremely morphologically variable, especially with regard to leaf shape, overall size, and habit. There seem to be no direct correlations between habitat type and morphology.

Mollugo verticillata possesses intermediate C3-C4 photosynthetic pathway characteristics, such as well- defined bundle-sheaths with numerous C4-like chloroplasts, distinct palisade and spongy parenchyma as in C3 plants, and intermediate light to dark ratios of CO2 evolution, which have made the species of particular interest in studies of the evolution and biochemistry of both photosynthetic pathways (R. A. Kennedy et al. 1980).

Plant: annual herb; glabrous, sometimes glaucous, stems mostly prostrate or ascending, to 28 (-40) cm long Leaves: of basal rosette to 40 mm long, to 10 (-16) mm wide, oblanceolate to obovate; cauline leaves to 20 (-36) mm long, 1-5 (-7) mm wide, oblanceolate Flowers: 1-several, pedicellate, sepals 5, 1.5-3 mm long, mostly 3-nerved; stamens usually 3, nearly equalling the sepals, pistils mostly 3-carpellate, the styles short or stigmas subsessile Fruit: FRUITS capsules, exceeding the sepals by 1/4-1/2 of their length, the apex 3-lobed. SEEDS numerous, ca. 0.6 mm, broadly reniform, the rounded back with (0-) 6-8 parallel dark brown ridges, the surface otherwise finely striate, shiny red-brown Misc: 800-2300 m (2600-7600 ft); Jul-Nov REFERENCES: Christy, Charlotte M. 1998. Molluginaceae. J. Ariz. - Nev. Acad. Sci. 30(2): 112..

Annual mat-forming herb to 40 cm across Stem: prostrate and highly branched. Leaves: borne in whorls of three to eight, short-stalked, 1 - 3 cm long, narrow and inversely egg-shaped and tapering to the base. Flowers: two to five per node, pale green to white, 4 - 5 mm across, with five sepals and three to four stamens. Fruit: a thin-walled three-chambered capule, egg-shaped, 3 mm long, breaking along partitions to reveal many ridged seeds.

Similar species: No information at this time.

Flowering: early June to early October

Habitat and ecology: Introduced from the southern United States, this species commonly occurs in disturbed sandy soils and is locally frequent in cindery railroad ballast and waste areas. It has become a weed in sandy cultivated fields.

Occurence in the Chicago region: non-native

Etymology: Mollugo is an old name for Galium mollugo. Verticillata means whorled, referring to the leaves.

Author: The Morton Arboretum

Wiggins 1964

Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Prostrate annual forming mats 1-35 cm across. Leaves: Spatulate, 5-6 in a whorl, 5-40 mm long, 2-8 mm wide, basal ones distinctly petiolate. Flowers: Several at node on slender pedicels, 5-15 mm long but not pedunculate, oblong sepals 2-2.5 mm long with green midrib and white margins; usually 3 stamens, alternating with cells of ovary about 1.5 mm long. Fruits: Ovoid capsule, slightly surpassing sepals. Ecology: Found in sandy soil and disturbed areas; 2,500-5,000 ft (762-1524 m); flowers September-October. Distribution: Cosmopolitan, on every continent in the world; throughout N. Amer. and in every state in the US. Notes: Fairly distinct as a small delicate, ascending to decumbent, hairless annual with whorled leaves and small white flowers which are single in the ends of petioles; can form dense patches. Ethnobotany: Unknown Etymology: Mollugo is an old name for the genus Galium, transferred because of similarly whorled leaves, while verticillata means whorled also. Synonyms: Mollugo berteriana Editor: SBuckley 2010, FSCoburn 2015

Glabrous annual, repeatedly forked, forming mats to 4 dm wide; lvs in whorls of 3-8, narrowly to broadly oblanceolate, 1-3 cm, tapering to a short petiolar base; fls 2-5 from each node, on pedicels 5-15 mm, pale green or white, 4-5 mm wide; stamens 3 or 4; fr ovoid, 3 mm; seeds numerous, arcuate-ridged; 2n=64. Apparently native to tropical Amer., but now a common weed in moist soil and dunes nearly throughout temperate N. Amer. June-Sept.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.

From Flora of Indiana (1940) by Charles C. Deam

The carpetweed is distributed throughout the state in dry or moist soils that are not covered with vegetation. It is infrequent, frequent or common where found, usually on the sandy shores of streams, in cultivated fields such as cornfields, stubble fields, and truck gardens, in ballast along railroads, along roadsides, and elsewhere in sandy soil.

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Indiana Coefficient of Conservatism: C = null, non-native

Wetland Indicator Status: FAC