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Idaho Fleabane - Erigeron asperugineus
State Rank Reason (see State Rank above)
Erigeron asperugineus is rare in Montana where it is known from approximately six occurrences in the southwestern portion of the state. Most occurrences have not been revisited in over 20 years. The total state population count is not well-documented but appears to be small, likely in the low thousands, which puts the species at higher risk of extirpation. Plants occur in remote habitats that are intact and in good condition; therefore, it is presumed that population trends are relatively stable. Threats to Erigeron asperugineus have not been identified, though negative impacts from a changing climate are suspected.
Surveys that gather current information on distributions, population counts, habitat conditions, and threats is greatly needed at all occurrences. Additional surveys into areas with potentially suitable habitat are needed and could locate 'new' occurrences.
General Description
Idaho Fleabane is a small perennial herb that is 2-20 cm tall. It has 1 to a few stems arising from a slender taproot. The basal leaves are up to 10 cm long, and have a broadly lance-shaped to nearly round blade and a long petiole. The few stem leaves are smaller and reduced upwards. The herbage is densely covered with short spreading hairs. The daisy-like, flowering heads are solitary (or, occasionally, there are 2) at the ends of the stalks. The involucral bracts are 5-9 mm long and covered with glands and spreading hairs. The 10-25 deep blue or violet rays that compose the petals of the flowering head are 5-10 mm long. The disk corollas in the center of the head are 4-6 mm long. The achenes have 20-30 bristles, forming a pappus, at their tops.
Phenology
Flowering occurs in July-August.
Diagnostic Characteristics
There are many species of high-elevation, low-growing, taprooted Erigeron, and it is difficult to distinguish among them. Erigeron evermannii and E. leiomerus have glabrous leaves. Hair on the stems of E. tweedyi and E. tener is appressed rather than spreading outward. The larger leaves of E. caespitosus have three nerves, while those of E. asperugineus have only one. Leaves of E. radicatus, E. ochroleucus and E. rydbergii are nearly linear; the petiole not distinguishable from the blade.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Central ID, northeast NV, and southwest MT. Regional endemic.
Observations in Montana Natural Heritage Program Database
Number of Observations: 9
(Click on the following maps and charts to see full sized version)
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
The species typically grows on windswept, rocky or gravelly slopes and ridges in alpine zones, often on limestone-derived soils. Associates that have been documented at Montana sites include Agropyron spicatum (dominant with cushion plants at one locality), Haplopappus acaulis, Phlox mulitflora, Arenaria congesta, Erigeron compositus, Senecio canus, Bupleurum americanum and Antennaria umbrinella.
National Vegetation Classification System Groups Associated with this Species
Alpine
Alpine - Sparse and Barren
Alpine - Vegetated
Ecology
Erigeron asperugineus is a low-growing plant, easily shaded by taller plants. It always occurs in sparse vegetation. One collection (possibly misidentified) from the 1960's referred to its habitat as "overgrazed."
POLLINATORS The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap:
Bombus bifarius,
Bombus centralis,
Bombus fervidus,
Bombus flavifrons,
Bombus huntii,
Bombus melanopygus,
Bombus mixtus,
Bombus rufocinctus,
Bombus occidentalis, and
Bombus insularis (Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Koch et al. 2012).
Management
The alpine habitat of E. asperugineus is at low risk from anthropogenic disturbance; however there are very few recent records, so it is difficult to make inferences about its status.
Stewardship Responsibility
Threats or Limiting Factors
Threats to Idaho Fleabane have not been reported though climate change poses a potential risk to the state's populations. The MTNHP conducted a species-level assessment using the Climate Change Vulnerability Index (CCVI) in 2021, which resulted in an Extremely Vulnerable rating to climate change. Climate change including increased ambient temperatures, decreased snowpacks, and increased frequencies and severities of drought could have negative impacts on this species; however, field-based data is not available. Since the timing and magnitude of impacts from a changing climate are unknown, this potential threat is not used in the calculation of the overall threat rank, score, or final subnational rank.
References
- Literature Cited AboveLegend:
View Online Publication
Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.- Koch, J., J. Strange, and P. Williams. 2012. Bumble bees of the western United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 143 p.
- MTNHP Threat Assessment. 2021. State Threat Score Assignment and Assessment of Reported Threats from 2006 to 2021 for State-listed Vascular Plants. Botany Program, Montana Natural Heritage Program, Helena, Montana.
- Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
- Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist 70(2): 198-207.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
- Web Search Engines for Articles on "Idaho Fleabane"
