This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial by stolons and offsets, villous-pubescent; stems simple, slender, 10'-24' high. Basal leaves tufted, spatulate or obovate, somewhat cuneate at the base, narrowed into short margined petioles, obtuse at the apex, 1'-3' long, 1/2'-2' wide, dentate or serrate; stem leaves sessile, partly clasping, oblong, lanceolate or ovate, mostly acute, entire, or sparingly serrate; heads 1-6, slender-peduncled, 1'- 1 1/2' broad; involucre depressed-hemispheric, its bracts linear, acuminate, villous; rays numerous, violet or purplish, 4"-7" long; achenes nearly glabrous; pappus simple.
Erigeron philadelphicus L. Sp. Pl. 863. 1753.
Perennial by stolons and offsets, soft-pubescent or sometimes nearly glabrous; stems slender, mostly branched above, 1°-3° high. Basal and lower leaves spatulate or obovate, obtuse, dentate, 1'-3' long, narrowed into short petioles; upper stem leaves clasping and often cordate at the base, obtuse or acute, dentate or entire; heads several or numerous, corymbose-paniculate, 5"-12" broad, slender-peduncled; peduncles thickened at the summit; involucre depressed-hemispheric, its bracts linear, usually scarious-mar-gined; rays 100-150, 2"-4" long, light rose-purple to pinkish; pappus simple; achenes puberulent.
Erigeron divergens T. & G. Fl. N. A. 2: 175. 1841.
Annual or biennial, diffusely branched, 6'-15'high, densely cinereous-pubescent or hirsute. Basal and lower leaves spatulate or oblanceolate, acute or obtuse, mostly petioled, entire, dentate or lobed, l'-2' long, 2"-5" wide, the upper sessile, linear or narrowly spatulate, usually acute, gradually smaller; heads slender-peduncled, 8"-12" broad, usually numerous; involucre hemispheric, about 2" high, its bracts linear, acute, hirsute or canescent; rays about 100, purplish, violet or nearly white, 2"-4" long; pappus double, the shorter outer row of bristles subulate.
In moist soil, Montana to Nebraska, Texas, Mexico, Washington and California. April-Sept.