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Home/Species/ Isely's Milkvetch

Astragalus iselyi

Welsh

Isely's Milkvetch

G1Critically Imperiled Found in 1 roadless area NatureServe Explorer →
G1Critically ImperiledGlobal Rank
Very highThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.132514
Element CodePDFAB0F4E0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderFabales
FamilyFabaceae
GenusAstragalus
Other Common Names
Isely's milkvetch (EN)
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.
Taxonomic Comments
Jones, Winkler and Massatti found "...low gene flow between three highly differentiated taxa (currently delineated as A. iselyi, A. sabulosus var. sabulosus and A. sabulosus var. vehiculus) that rapidly diverged from a small ancestral population near the beginning of the last glacial period" (Jones et al. 2021).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2022-08-23
Change Date1994-03-05
Edition Date2022-08-23
Edition AuthorsNiese, J. (1994-03-05); rev. B. Franklin (1996); B. Franklin (2007); rev. A. Treher (2011), rev. C. Nordman (2022).
Threat ImpactVery high
Range Extent250-1000 square km (about 100-400 square miles)
Number of Occurrences6 - 20
Rank Reasons
Isely's Milkvetch is a narrow endemic of southeastern Utah, known from 3 general areas astride the Grand-San Juan county line; the single Grand County location being disjunct 22.5 km to the northeast. The nunber of plants varies from year to year, and numbers were particularly low in 2019 following severe drought. Off road vehicles are a threat and uranium exploration and mining has occurred within the species' habitat in the past and recent prices have sparked a renewed interest.
Range Extent Comments
Isely's Milkvetch occurs in the western United States, only in Utah. It is an extremely narrow endemic found on the west slope of the La Sal Mountains, in Grand (a single location) and San Juan counties, Utah. The range extent is estimated to be 264 square kilometers (NatureServe 2022, Utah Natural Heritage Program 2021).
Occurrences Comments
There are estimated to be 8 occurrences, based on 2 km separation distances (NatureServe 2022, Utah Natural Heritage Program 2021).
Threat Impact Comments
The area where Isely's Milkvetch occurs is subject to heavy grazing, some mining and recreation use, and ORV activities. The ongoing renewal of mining claims in the uranium rich habitat on which this plant grows is a concern (Franklin 2003, USFWS 2009). This plant seems to rely on a seed bank, in 2019 no live adult or juvenile plants, only seedlings were seen at Brumley Ridge, the most extensive occurrence (Utah Natural Heritage Program 2021). Severe drought exacerbated by climate change is also a threat.
Ecology & Habitat

Diagnostic Characteristics

Similar to A. sabulosus var. sabulosus but differs in the smaller white flowers (17-19 mm long vs. 27-24 mm) and the shorter calyx tube (5.5-6.3 mm long vs. 11-5-14 mm).

Habitat

Astragalus iselyi occurs on seleniferous and gypsiferous sandy to gravelly clay slopes of the uranium-rich soils derived from the Morrison (3 locations), Paradox (1 location) and Mancos formations at 1525 to 2010 m elevation in pinyon-juniper and desert scrub communities (Goodrich er al. 1999).
Terrestrial Habitats
Forest/WoodlandWoodland - ConiferDesertBarrens
Other Nations (1)
United StatesN1
ProvinceRankNative
UtahS1Yes
Threat Assessments
ThreatScopeSeverityTiming
2 - Agriculture & aquacultureLarge (31-70%)Slight or 1-10% pop. declineHigh (continuing)
2.3 - Livestock farming & ranchingLarge (31-70%)Slight or 1-10% pop. declineHigh (continuing)
3 - Energy production & miningPervasive (71-100%)Serious or 31-70% pop. declineHigh (continuing)
3.2 - Mining & quarryingPervasive (71-100%)Serious or 31-70% pop. declineHigh (continuing)
4 - Transportation & service corridorsLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
4.1 - Roads & railroadsLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
6 - Human intrusions & disturbanceSmall (1-10%)Slight or 1-10% pop. declineHigh (continuing)
6.1 - Recreational activitiesSmall (1-10%)Slight or 1-10% pop. declineHigh (continuing)
11 - Climate change & severe weatherPervasive (71-100%)Moderate or 11-30% pop. declineHigh (continuing)
11.2 - DroughtsPervasive (71-100%)Moderate or 11-30% pop. declineHigh (continuing)

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Plant Characteristics
DurationPERENNIAL, Short-lived
Economic Value (Genus)Yes
Roadless Areas (1)
Utah (1)
AreaForestAcres
Horse Mountain - Mans PeakManti-Lasal National Forest22,159
References (12)
  1. Barneby, R.C. 1989. Fabales. In A. Cronquist, A.H. Holmgren, N.H. Holmgren, J.L. Reveal, and P.K. Holmgren (eds.). Intermountain flora: Vascular plants of the Intermountain West, U.S.A. Vol. 3, Part B. New York Botanical Garden, Bronx. 279 pp.
  2. Franklin, B. 2003. Data from the Utah Natural Heritage Program.
  3. Franklin, M.A. 2005. Plant information compiled by the Utah Natural Heritage Program: A progress report. Publication Number 05-40. Utah Division of Wildlife Resources, Salt Lake City, Utah. 341 pp. [http://dwrcdc.nr.utah.gov/ucdc/ViewReports/plantrpt.htm]
  4. Goodrich, S., L. Armstrong, and R.Thompson. 1999. Endemic and endangered plants of Pinyon Juniper communities. USDA Forest Service Proceedings RMRS-P-9 260-268.
  5. Jones, M.R., D.E. Winkler, R. Massatti. 2021. The demographic and ecological factors shaping diversification among rare <i>Astragalus</i> species. Diversity and Distributions 27:1407–1421. Online. Available: https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/ddi.13288 (Accessed 2022).
  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. NatureServe. 2022. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  8. Spahr, R., L. Armstrong, D. Atwood, and M. Rath. 1991. Threatened, endangered, and sensitive species of the Intermountain Region. U.S. Forest Service, Ogden, Utah.
  9. U.S. Fish and Wildlife Service (USFWS). 2009. Endangered and Threatened Wildlife and Plants; Partial 90-Day Finding on a Petition To List 206 Species in the Midwest and Western United States as Threatened or Endangered With Critical Habitat. Federal Register 74(158): 41649-41662. 18 August 2009.
  10. U.S. Fish and Wildlife Service (USFWS). 2022. Endangered and Threatened Wildlife and Plants; One Species Not Warranted for Delisting and Seven Species Not Warranted for Listing as Endangered or Threatened Species. Federal Register 87(249):80080-80088.
  11. Utah Natural Heritage Program. 2021. Utah Rare Plant Database (accessed 2021).
  12. Welsh, S.L., N.D. Atwood, L.C. Higgins, and S. Goodrich, eds. 1987. A Utah Flora. Great Basin Naturalist Memoir 9: 1- 894. Brigham Young University, Provo, Utah. 894 pp.