Flora of North America species comparison

A. E. Porsild (1975) noted that in Yukon, var. pubescens “is well established along highways and townsites, near existing and former gold-mining camps, and was most likely introduced with shipments of baled hay in the early years of gold mining.”

Plants with appressed cauline vestiture (var. glabellus) are more common in the southern range, while, at least in Alaska, Yukon, Northwest Territories, Alberta, and British Columbia, plants mostly have spreading cauline vestiture (var. pubescens). The two taxa apparently overlap over a considerable area, however, and some individual collections show plants similar in all respects except stem vestiture: some have antrorsely appressed hairs and some have spreading hairs (e.g., Saskatchewan: Ledingham 46-2, 46-19, 48-112, all BRIT; New Mexico: Talbot 1093, LL). Marked variability within Erigeron glabellus is emphasized by the many names proposed at specific rank for forms of the species, mostly by Greene and Lunell (see A. Cronquist 1947). The biology and taxonomy of this complex need modern study.

(Discussion copyrighted by Flora of North America; reprinted with permission.)