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Home/Species/ Branched Fleabane

Erigeron allocotus

Blake

Branched Fleabane

G4Apparently Secure Found in 3 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
LowThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.151720
Element CodePDAST3M050
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderAsterales
FamilyAsteraceae
GenusErigeron
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-02-27
Change Date2025-02-27
Edition Date2025-02-24
Edition AuthorsMarriott, H. (1989), rev. C. Nordman (2025).
Threat ImpactLow
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences21 - 300
Rank Reasons
Branched Fleabane (Erigeron allocotus) occurs in the Rocky Mountains of western United States. It is a regional endemic plant of talus, cliffs and rocky areas which occurs in the Bighorn and Pryor ranges and adjacent foothills in north-central Wyoming and south-central Montana. It is estimated there are about 84 and between 21 and 300 occurrences rangewide, mostly on BLM and USDA Forest Service lands, including with protective designations such as Wilderness Study Areas, and ACECs. Much of the known habitat of Erigeron allocotus is very inaccessible, cushion plant communities are potentially vulnerable, but the overall threat is low. Some occurrences may be threatened by trampling, such as by livestock, hikers, or other recreational activities.
Range Extent Comments
Branched Fleabane (Erigeron allocotus) occurs in the Rocky Mountains of western United States. It is a regional endemic plant which occurs in the Bighorn and Pryor ranges and adjacent foothills in north-central Wyoming and south-central Montana. Range extent was estimated using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (FNA 2006, GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2024, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated there are about 84 and between 21 and 300 occurrences rangewide (RARECAT 2024, GBIF 2025, iNaturalist 2025, NatureServe 2025, SEINet 2025).
Threat Impact Comments
Much of the known habitat of Erigeron allocotus is very inaccessible, cushion plant communities are potentially vulnerable, but the overall threat is low. Some occurrences may be threatened by trampling, such as by livestock, hikers, or other recreational activities (NatureServe 2025).
Ecology & Habitat

Description

Bighorn fleabane is a multi-branched perennial herb with leafy stems 13-18 cm tall. Stems and leaves are conspicuously pubescent with coarse, spreading hairs. The leaves may also be finely glandular and are divided at the tip into 3-5 teeth or linear segments. Basal leaves are 1.5-3 cm long, while stem leaves are mostly under 1 cm and simple to 3-toothed. Flowering heads are small and numerous, each having a 4-5 mm high involucre of glandular and hirsute bracts, 25-40 white to pinkish ray flowers (3-6 mm long), and a yellow-flowered disk 6-9 mm wide (disk corollas 2-3.5 mm long). The pappus consists of 12-20 bristles 2-2.5 mm long. Fruits are 2-nerved achenes with short stiff hairs (Blake 1937, Cronquist 1947 both cited in Heidel and Fertig 2000, Dorn 1992, Marriott and Jones 1989).

Diagnostic Characteristics

"The brittle, hispid vestiture, and multiple small heads (more than one per stem) with short rays of Erigeron allocotus are unusual among its putative relatives with 3-parted leaves" (FNA 2006).

Habitat

Erigeron allocotus occurs on dry, rocky calcareous sites of limestone or less often sandstone, such as "cliff faces, ledges, talus slopes, ridgetops, rock outcrops, barren redbeds, sometimes with Utah juniper, mountain mahogany, or sagebrush" at elevations of 1300–2300 m (FNA 2006, SEINet 2025).

Reproduction

Flowering May to August, the seeds with bristles, suitable for dispersal by mammals (FNA 2006).
Terrestrial Habitats
Bare rock/talus/screeCliff
Other Nations (1)
United StatesN4
ProvinceRankNative
WyomingS3Yes
MontanaS3Yes
Threat Assessments
ThreatScopeSeverityTiming
2 - Agriculture & aquacultureRestricted (11-30%)Moderate - slightHigh (continuing)
2.3 - Livestock farming & ranchingRestricted (11-30%)Moderate - slightHigh (continuing)
6 - Human intrusions & disturbanceSmall (1-10%)Moderate - slightHigh (continuing)
6.1 - Recreational activitiesSmall (1-10%)Moderate - slightHigh (continuing)

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Plant Characteristics
DurationPERENNIAL, SUMMER-FLOWERING
Economic Value (Genus)No
Roadless Areas (3)
Wyoming (3)
AreaForestAcres
Cloud Peak ContiguousBighorn National Forest113,757
Horse Creek MesaBighorn National Forest77,808
Leigh CreekBighorn National Forest19,180
References (10)
  1. Dorn, R.D. 1992. Vascular plants of Wyoming, 2nd edition. Mountain West Publishing, Cheyenne, Wyoming.
  2. Flora of North America Editorial Committee (FNA). 2006b. Flora of North America north of Mexico. Vol. 20. Magnoliophyta: Asteridae, part 7: Asteraceae, part 2. Oxford Univ. Press, New York. xxii + 666 pp.
  3. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  4. Heidel, B. and W. Fertig. 2000. Rare plants of Bighorn Canyon National Recreation Area. Report to the National Fish and Wildlife Foundation and Bighorn Canyon National Recreation Area, National Park Service. Montana Natural Heritage Program and Wyoming Natural Diversity Database. Helena and Laramie. 63 pp. plus appendices.
  5. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  6. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  7. Marriott, H. J., and G. P. Jones. 1989. Special status plant surveys and plant community surveys in the Trapper Creek and Medicine Lodge Wilderness Study Areas and the Spanish Point Karst ACEC. Report submitted to the Bureau of Land Management, Worland District Office, under Cooperative Agreement Task Order No. WY910-CA9-001TQE1. Wyoming Natural Diversity Database, Laramie. 42 pp. plus appendices.
  8. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  9. NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2024. Version: 1.1.1 (released Oct 01, 2024).
  10. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).