169. Erigeron annuus (Linnaeus) Persoon, Syn. Pl. 2: 431. 1807.
Eastern daisy fleabane, vergerette annuelle
Aster annuus Linnaeus, Sp. Pl. 2: 875. 1753; Erigeron annuus var. discoideus (Victorin & J. Rousseau) Cronquist
Annuals, (10–)60–150 cm; fibrous-rooted or taprooted. Stems erect, sparsely piloso-hispid (hairs spreading), sometimes strigose distally, eglandular. Leaves basal (usually withering by flowering) and cauline; basal blades mostly lanceolate to oblanceolate or ovate, 15–80 × 3–20 mm, margins coarsely serrate to nearly entire, faces sparsely strigoso-hirsute, eglandular; cauline lanceolate to oblong, little reduced proximal to midstem. Heads ca. 5–50+ in loosely paniculiform or corymbiform arrays. Involucres 3–5 × 6–12 mm. Phyllaries in 2–3(–4) series, sparsely villous or hirsuto-villous, minutely glandular. Ray florets 80–125; corollas white, 4–10 mm, laminae tardily coiling. Disc corollas 2–2.8 mm. Cypselae 0.8–1 mm, 2-nerved, faces sparsely strigose; pappi: outer minute crowns of setae or narrow scales, inner 0 (rays) or of 8–11 bristles (disc). 2n = 27.
Flowering Jun–Aug(–Nov). Mostly open, disturbed habitats, especially roadsides, fields, waste areas; 0–500(–2200) m; St. Pierre and Miquelon; B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Sask.; Ala., Ark., Calif., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis.; Mexico (Hidalgo); Central America (Costa Rica, Nicaragua, Panama); Europe; Asia.
Erigeron annuus is apparently native to eastern North America (United States and southern Canada) and is introduced elsewhere; it probably occurs in North Dakota and Alberta; apparently it has not been documented there. Apparent intermediates between E. annuus and E. strigosus are encountered.