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..
Erigeron pumilis Nutt. Gen. 2: 147. 1818.
Perennial by a deep root; stems tufted, hirsute, slender, simple, or branched, 4'-10' high. Leaves entire, hirsute, the lower and basal ones narrowly spatulate or linear, petioled, obtuse or acutish, 1'-4 long, 1"-2" wide; stem leaves linear, sessile, 1/2'-2 1/2' long, acute; heads solitary or several, 6"-10" broad, short-peduncled; involucre hemispheric, its bracts linear, acute, hirsute; rays 50-80, white, 3"-4" long, at length deflexed; pappus double, the outer row of bristles short and more or less intermixed with the inner; achenes pubescent.
Dry plains, North Dakota to western Nebraska, Kansas, British Columbia, Colorado and Utah. May-Sept.
Perennial by a deep woody root, resembling the preceding species; stems slender, erect, tufted, appressed-canescent, 6'-10' high, simple, or branched above. Leaves narrow, entire, canescent, the basal and lower ones narrowly spatulate, petioled, 2'-4' long, the upper linear, sessile, acute, gradually smaller; heads solitary, or 2-4, peduncled, 6"-8" broad; involucre hemispheric, its bracts linear, acute, densely canescent; rays 40-50, purple or white, 2"-3" long; achenes glabrous, 8-10-nerved; pappus double, the outer row of bristles rather conspicuous.
In dry soil, South Dakota to western Nebraska, Wyoming. Colorado and New Mexico. June-Aug.
Erigeron hyssopifolius Michx. Fl. Bor. Am. 2: 123.
1803. Aster graminifolius Pursh, Fl. Am. Sept. 545. 1814.
Perennial by slender rootstocks; stems tufted or single, very slender, simple or branched, glabrous or very nearly so, 4'-15' high. Leaves narrow, thin, the basal and lower ones oblong or spatulate, short-petioled, 1'-1 1/2' long, 1 1/2"-2" wide, the upper linear or linear-oblong, acute, usually numerous; heads solitary or several, slender-peduncled, 5"-8" broad; peduncles appressed-pubescent; involucre nearly cylindric at flowering time, its bracts linear-lanceolate, sparingly pubescent; rays 12-30, white or purplish, 3"-6" long; pappus simple.
On moist cliffs, Newfoundland to northern Vermont, Mackenzie and Lake Superior. July-Aug.
Erigeron flagellaris A. Gray, Mem. Am. Acad. (II) 4: 68. 1849.
Appressed-pubescent, sometimes densely so, perennial by decumbent rooting stems or stolons; root slender; stem slender, branched, the branches elongated. Leaves entire, the basal and lower ones spatulate or oblong, obtuse or acute, 1'-2' long, narrowed into long petioles, the upper sessile, linear or linear-spatulate, much smaller; peduncles solitary, elongated; heads about 1' broad and 1/4' high; involucre hemispheric, its narrow bracts pubescent; rays very numerous, white to pink; pappus double, the outer series of subulate bristles.
In moist soil, South Dakota to Wyoming, Utah, western Texas and New Mexico. May-July.