Astragalus rafaelensis
Author: M.E. Jones

San Rafael milkvetch

Fabaceae (Pea Family)

Close up of Astragalus rafaelensis by Peggy Lyon.
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Close up of Astragalus rafaelensis by Peggy Lyon.
Click image to enlarge.

Ranks and Status

Global rank: G2G3
State rank: S1
Federal protection status: BLM Sensitive
State protection status: None

[+] Description and Phenology

Please see 1997 profile.

General description: Perennials, 4-5 dm tall. Inflorescence with 6-12 flowers, usually pink-purple and white tipped. Pods sessile, mostly reflexed, although there may be some upright pods on the same plant. Pods are glabrous, ellipsoid to oblong, and laterally compressed (Ackerfield 2015, Spackman et al. 1997). Plants broomy, with many old stems forming thatch at base of plant. Leaves extremely narrow and reduced.

Look Alikes: Astragalus linifolius has erect pods (Ackerfield 2015). The two species have apparently hybridized near Uravan. Astragalus saurinus differs in that it has longer, narrower, and less fleshy pods (Spackman et al. 1997).

Phenology: Flowers late April through June. Fruits in June (Colorado Natural Heritage Program 2015).

[+] Habitat

Habitat of Astragalus rafaelensis by Peggy Lyon.
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Habitat of Astragalus rafaelensis by Peggy Lyon.
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Gullied hills, washes, and talus under cliffs; in seleniferous clayey, silty, or sandy soils. (Spackman et al. 1997). Asociated plant community: Pinus edulisJuniperus osteospermaCercocarpus montanus. Additional associated plant species: Purshia tridentata, P. stansburiana, Elymus elymoides, Petradaria pumila, Physaria acutifolia, Senecio multilobatus, Erysimum capitatum, Hymenopappus filifolius, Haplopappus armerioides, Lepidium montanum, Oryzopsis hymenoides, Astragalus lonchocarpusChaetopappa ericoidesPoa secundaCastilleja chromosaAstragalus flavusErigeron pumilusHymenoxys richardsoniiCastilleja seabridaPediomelum megalanthumGutierrezia sarothraeAstragalus wetherilliiSchoenocrambe linifoliaTownsendia incanaAstragalus eastwoodiae, Heterotheca villosa.

Elevation Range: 4,724 - 6,788 feet (1,440 - 2,069 meters)

[+] Distribution

Distribution of Astragalus rafealensis in Colorado according to mapped land ownership/management boundaries (CNHP 2015, COMaP v9).
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Distribution of Astragalus rafaelensis in Colorado.
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Colorado endemic: No
Global range: In Utah in Emery and Grand counties, and in Colorado in Montrose and Mesa counties.
State range: Known from Mesa and Montrose counties in Colorado. Estimated range in Colorado is 1459 square kilometers (563 square miles), calculated in GIS by the Colorado Natural Heritage Program in 2008 by drawing a minimum convex polygon around the known occurrences. Also known from Utah. 

[+] Threats and Management Issues

Summary results of an analysis of the status of Astragalus rafaelensis based on several ranking factors. This species was concluded to be “Moderately Conserved”. From Rondeau et al. 2011.
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The Colorado occurrences are within BLM lands with no special protection status. This species occurs at low elevation and is potentially threatened by development, and road and bridge maintenace.

[+] References

    • Ackerfield, J. 2015. Flora of Colorado. Brit Press, Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.
    • Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.
    • Cronquist A. 1989. Intermountain Flora Vascular Plants of the Intermountain West, USA. Vol. 3, Part B. New York Botanical Garden, Bronx, NY.
    • 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.
    • Neely, B., S. Panjabi, E. Lane, P. Lewis, C. Dawson, A. Kratz, B. Kurzel, T. Hogan, J. Handwerk, S. Krishnan, J. Neale, and N. Ripley. 2009. Colorado Rare Plant Conservation Strategy, Developed by the Colorado Rare Plant conservation Initiative. The Nature Conservancy, Boulder, Colorado, 117 pp.
    • Spackman, S., B. Jennings, J. Coles, C. Dawson, M. Minton, A. Kratz, and C. Spurrier. 1997. Colorado rare plant field guide. Prepared for Bureau of Land Management, U.S. Forest Service and U.S. Fish and Wildlife Service by Colorado Natural Heritage Program.
    • USDA, NRCS. 2013. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.
    • Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora, Western Slope, A Field Guide to the Vascular Plants, Fourth Edition. Boulder, Colorado. 532 pp.
    • Weber, W.A., and R.C. Wittmann. 1996a. Colorado flora: Eastern slope. Revised edition. Univ. Press of Colorado, Niwot, Colorado. 524 pp.
    • Welsh, S.L., N.D. Atwood, S. Goodrich and L.C. Higgins. (Eds.) 2003. A Utah Flora. 3rd edition. Brigham Young University, Provo, Utah, U.S.A. 912 pp.
    • Welsh, S.L., N.D. Atwood, S. Goodrich, and L.C. Higgins (eds.) 1993. A Utah flora. 2nd edition. Brigham Young Univ., Provo, Utah. 986 pp.

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