Erigeron acris var. kamtschaticus (DC.) Herder
Click to enlarge
Erigeron angulosus var. kamtschaticus, Erigeron acris ssp. politus, Erigeron acris var. asteroides
Basis for Listing
Erigeron acris var. kamtschaticus (bitter fleabane) is a circumboreal species that ranges southward into mountainous regions and other boreal habitats. It occurs in northeastern Minnesota, where rugged topography and the climate-modifying effects of Lake Superior influence the southerly reaches of the boreal biome (North Shore Highlands Subsection). Although E. acris var. kamtschaticus was first documented in Minnesota in 1929 from the Susie Islands (Cook County) in Lake Superior, it was not recorded again until 1944 and 1945 at Pigeon Point on Lake Superior and the Cascade River (Cook County), respectively. None of these populations have since been relocated. Upon review of the species’ status in 1996, the historical record clearly indicated E. acris var. kamtschaticus was rare in Minnesota but did not provide enough information for botanists to assign a status of endangered or threatened. For that reason, it was listed as special concern in 1996.
In 2000, over 55 years since last reported in Minnesota, a small population of E. acris var. kamtschaticus was discovered in northern Lake County. In 2008, another population was found along a Lake Superior stream canyon in Cook County. As of 2013, these were the only two known locations for E. acris var. kamtschaticus in Minnesota. However, the Lake County population has been searched for twice since its discovery with no success. This could reflect the difficulty of relocating small populations in steep and rugged landscapes or possibly the ephemeral nature of some populations. The small sizes of the Minnesota populations (4-7 flowering plants) are also of conservation concern. Upon evaluating the new information, in 2013 a status of endangered was assigned to Erigeron acris var. kamtschaticus.
Erigeron acris var. kamtschaticus has ray laminae that are filiform, very short, and inconspicuous. Pappus bristles are accrescent (elongating in fruit to approximately 2 times the length of the involucre), giving the plant a cottony appearance as it matures (see image). Leaves are tapered (spatulate-oblanceolate), non-clasping at the base, and reduced in size distally. There are six other species which occur in Minnesota that are similar to Erigeron acris var. kamtschaticus, but only three of them are found in the Arrowhead region. These include Erigeron annuus (annual fleabane), E. philadelphicus var. philadelphicus (Philadelphia fleabane), and E. strigosus (daisy fleabane). Each of these species has ray laminae that are strap-shaped and quite conspicuous, appearing more like a dainty aster. Their pappus bristles are non-accrescent, and they do not elongate in fruit.
Erigeron acris var. kamtschaticus is known to occur on the steep canyon walls of a Lake Superior stream in a northern mesic hardwood forest with Diervilla lonicera (bush honeysuckle), Acer spicatum (mountain maple), Cornus sericea (red-osier dogwood), Sorbus decora (showy mountain ash), Campanula rotundifolia (harebell), and Achillea millefolium (common yarrow). It also occurs in a northern mesic mixed forest on a steep and rocky westerly-facing slope, 3 km (2 mi.) inland from Lake Superior with Betula papyrifera (paper birch), Thuja occidentalis (northern white cedar), Abies balsamea (balsam fir), Rubus idaeus var. strigosus (red raspberry), Dryopteris fragrans (fragrant fern), Cystopteris fragilis (fragile fern), and Woodsia ilvensis (rusty woodsia). Historic populations in Minnesota were reported from the rock crevices and shores of Lake Superior. Across its range, E. acris var. kamtschaticus is reported to occur in rocky to sandy sites, riverbanks, roadsides, and disturbed areas (Nesom 2006) and clearings, open B. papyrifera woods, and sandy shaded banks (Voss 1996).
Biology / Life History
Erigeron acris var. kamtschaticus can be an annual, biennial, or a short lived perennial. At this time, we know very little about it in our state, other than it occurs here. Even though it was first observed in Minnesota in 1929, those populations could not be relocated. With the discovery of new populations, we are again provided a window of opportunity to learn and conserve. The two known populations of plants in the state have very low numbers of individual flowering plants (4-7) and also support low numbers of accompanying sterile rosettes.
Conservation / Management
One of the most recent discoveries of E. acris var. kamtschaticus is within the boundary of a state park, which could potentially provide stewardship and support for protection and conservation actions. However, even natural areas in state parks can be threatened by a host of recreational activities and nearby developments. The other known population of E. acris var. kamtschaticus is on land being managed by the county, with the adjacent cliff and rock outcrop plant communities threatened by recreational activities, including rock climbing and trails. Global climate change and the spread and establishment of invasive species also threaten the most remote natural places of Minnesota.
Best Time to Search
Erigeron acris var. kamtschaticus plants are identifiable and beginning to flower in late July. The best time to search for this species may be when it becomes most conspicuous, in mid- to late August as the fruit matures and the flowering heads appear as showy, cottony balls. One can easily pass by the plants, incorrectly assuming they are one of our common composites at either an immature or more mature stage of development.
Conservation Efforts in Minnesota
It is uncertain why the historic populations of this species have not been relocated in Minnesota. Recent survey efforts in the North Shore Highlands Subsection documented only a single new location. It could be that the historic populations were small and did not remain viable or that they were lost due to natural or anthropogenic disturbance events. A systematic inventory of potential habitat is ongoing and includes portions of Cook, Lake, and St. Louis counties.
Welby Smith (MNDNR), 2008 and 2018
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Given, D. R., and J. H. Soper. 1981. The arctic-alpine element of the vascular flora at Lake Superior. National Museum of Canada, Publications in Botany No. 10, Ottawa, Ontario. 70 pp.
Nesom, G. L. 2006. Erigeron. Pages 256-348 in Flora of North America Editorial Committee, editors. Flora of North America North of Mexico. Volume 20. Oxford University Press, New York, New York.