Erigeron radicatus

Nesom (2004) re-circumscribes Erigeron radicatus and E. ochroleucus for his Flora of North America treatment, stating that "confusion has existed in the distinction between Erigeron radicatus and E. ochroleucus, but the hypothesis is advanced here that they are distinct species sympatric over a significant area. In this view, E. radicatus has a wider geographic distribution than previously recognized and E. ochroleucus is more restricted in range." Nesom thus adds southeastern Wyoming, South Dakota, Nebraska, Colorado, and Utah to the range of E. radicatus. This record is for E. radicatus in the more narrow sense of Kartesz (1999), excluding those parts of the distribution.

This predominantly alpine to subalpine herb is known from western and central Montana, east-central Idaho, western Wyoming, southern and western Alberta, southern Saskatchewan, and west-central North Dakota. Approximately 34 occurrences are presumed extant in WY, AB, SK, and ND; at least 6, and possibly more, sites are known in ID. In Montana, known from at least a dozen mountain ranges and over two dozen specimen collections. In Montana, most collections describe the abundance as common at the collection site, with reports of some locally abundant sites in Wyoming and Saskatchewan as well; a few populations in the low hundreds of plants have been counted throughout the range. Threats to most populations are assumed to be low (and populations are assumed to be stable) due to the rugged, high-elevation habitat. However, some Alberta occurrences occur in dry mixedgrass prairie, where they are potentially threatened by land conversion or overgrazing, and three recently-noted Saskatchewan occurrences may soon be destroyed by a proposed mine.

Known from western and central Montana (at least a dozen mountain ranges); east-central Idaho (at least the Lost River ,Lemhi, and Beaverhead Ranges); western Wyoming (at least the Beartooth, Absaroka, Wyoming, Gros Ventre, and northern Wind River ranges); southern and western Alberta, where it has a broad but highly disjunct range with occurences in montane and subalpine regions, as well as dry mixedgrass prairie; southern Saskatchewan; and west-central North Dakota (Dunn County). Using GIS tools, total range extent was calculated to be approximately 700,000 km2.

Approximately 34 occurrences are presumed extant in Wyoming, Alberta, Saskatchewan, and North Dakota, with an additional 11 occurrences not recently revisited in Alberta and Saskatchewan. Idaho and Montana do not currently track this species; the number of occurrences in those states is unknown. In Idaho, the species was known from 6 recently-visited sites as of 1990 (US Forest Service 1990); in that year, it was removed from Idaho's "Plants of Conservation Concern" list, for reason "common, no threat." However, it appears that the primary reason for its removal was lack of threats rather than discovery of many additional sites; in 1999, Michael Mancuso (pers. comm.) described its status as "not known from tons of sites in Idaho, but few threats within its high-elevation habitat." In Montana, it is "known from at least a dozen mountain ranges and over two dozen specimen collections from western and central Montana. MT is not currently tracking occurrences due to its overall abundance, widespread distribution in the state and apparent lack of threats due to its high elevation habitat" (S. Mincemoyer pers. comm. 2008).

Most occurrences are found at high elevations in the mountains, where threats are low. However, some Alberta occurrences occur in dry mixedgrass prairie, where they are potentially threatened by land conversion or overgrazing. Three recently-noted Saskatchewan occurrences may soon be destroyed by a proposed mine. Recreational livestock were noted as a potential threat to the species in the Shoshone National Forest, Wyoming (Proctor and Austin 2002).