Conyza canadensis

(Linnaeus) Cronquist

Bull. Torrey Bot. Club 70: 632. 1943.

Common names: Vergerette du Canada
Illustrated
Basionym: Erigeron canadensis Linnaeus Sp. Pl. 2: 863. 1753 (as canadense)
Synonyms: Conyza canadensis var. glabrata (A. Gray) Cronquist Conyza canadensis var. pusilla (Nuttall) Cronquist Conyza parva E. canadensis var. pusillus (Nuttall) B. Boivin
Treatment appears in FNA Volume 20. Treatment on page 350. Mentioned on page 349.

Plants erect, (3–)50–200(–350+) cm, branched mostly distally. Leaves: faces usually glabrate (proximal margins ± ciliolate, hairs usually stiff, spreading and hispid on nerves, hairs erect); proximal blades oblanceolate to linear, 20–50(–100+) × 4–10(–15+) mm, toothed to entire; distal similar, smaller, entire. Heads usually in paniculiform, sometimes corymbiform arrays. Involucres 3–4 mm. Phyllaries usually glabrous, sometimes sparsely strigose (margins chartaceous to scarious); outer greenish to stramineous, lanceolate to linear, shorter; inner stramineous to reddish, lance-attenuate to linear. Receptacles 1–1.5(–3) mm diam. in fruit. Pistillate florets 20–30(–45+); corollas ± equaling or surpassing styles, laminae 0.3–1 mm. Disc florets 8–30+. Cypselae uniformly pale tan to light gray-brown, 1–1.5 mm, faces sparsely strigillose; pappi of 15–25, white bristles 2–3 mm. 2n = 18.


Phenology: Flowering year round, mostly summer–fall.
Habitat: Disturbed places
Elevation: 0–2000 m

Distribution

V20-806-distribution-map.gif

Alta., B.C., Man., N.S., Ont., P.E.I., Que., Sask., Ala., Ariz., Ark., Calif., Colo., Conn., 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., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Mexico, Central America, introduced in South America, Europe, Asia, Africa.

Discussion

Conyza canadensis is thought to be native to North America and is now widely adventive, e.g., in South America, Europe, Asia, and Africa. Plants with stems glabrous and phyllaries red-tipped are sometimes treated as var. pusilla; similar plants with stems glabrous and phyllaries stramineous (not red-tipped) are sometimes treated as var. glabrata.

Selected References

None.

Lower Taxa

None.
... more about "Conyza canadensis"
John L. Strother +
(Linnaeus) Cronquist +
Erigeron canadensis +
Vergerette du Canada +
Alta. +, B.C. +, Man. +, N.S. +, Ont. +, P.E.I. +, Que. +, Sask. +, Ala. +, Ariz. +, Ark. +, Calif. +, Colo. +, Conn. +, 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. +, Tex. +, Utah +, Vt. +, Va. +, Wash. +, W.Va. +, Wis. +, Wyo. +, Mexico +, Central America +, introduced in South America +, Europe +, Asia +  and Africa. +
0–2000 m +
Disturbed places +
Flowering year round, mostly summer–fall. +
Bull. Torrey Bot. Club +
Illustrated +
Conyza canadensis var. glabrata +, Conyza canadensis var. pusilla +, Conyza parva +  and E. canadensis var. pusillus +
Conyza canadensis +
species +