Annuals, biennials, or short-lived perennials, 30-70 cm; fibrous-rooted, caudices simple, sometimes lignescent, sometimes producing rhizomes that bear leaf tufts at upturned ends. Stems erect or ascending, sparsely to moderately strigose to strigillose or hirsuto-strigillose (hairs usually ascending, rarely spreading, 0.1-1.2 mm), eglandular. Leaves basal (usually persistent through flowering) and cauline; basal blades spatulate to broadly or narrowly oblanceolate to linear, (10-)30-150(-170) × 5-15(-21) mm, cauline usually gradually reduced distally, continuing to near heads, margins entire or shallowly to deeply serrate or crenate, faces glabrous or glabrate to sparsely strigose or strigoso-hirsute, eglandular. Heads 10-200+ in loosely corymbiform to paniculiform-corymbiform arrays (on distal branches). Involucres (2-)3-4 × 5-12 mm. Phyllaries in 2-4 series, glabrous, strigose, or sparsely hirsute, sometimes minutely glandular. Ray florets 50-100; corollas white, less commonly pinkish or bluish, 4-6 mm, laminae coiling. Disc corollas 1.5-2.5 mm (throats sometimes slightly indurate and inflated). Cypselae (0.5-)0.9-1.2 mm, 2-nerved, faces sparsely strigose; pappi: outer crowns of setae or scales, inner 0 (rays) or of 8-15 bristles (disc).
Annual or rarely biennial, 3-7(-12) dm, sparsely leafy, ±hairy, the hairs spreading or usually mostly appressed; basal lvs mostly oblanceolate to elliptic, entire or toothed, not over 15 cm (petiole included) נ2.5 cm; cauline lvs linear to lanceolate, mostly entire; heads several to very many; invol 2-5 mm, obscurely glandular and ±hairy; disk 5-12 mm wide; rays 50-100, white, or occasionally pinkish or bluish, to 6 mm, 0.4-1.0 mm wide, or much reduced; disk-cors 1.5-2.5 mm; pappus as in no. 7 [Erigeron annuus (L.) Pers.]; 2n=18, 27, 36, 54. A weed in disturbed sites over most of the U.S. and s. Can. (E. ramosus) Four vars.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.