Astragalus piscator
Author: Barneby & Welsh


Fisher Towers milkvetch


Fabaceae (Pea Family)

Close up of Astragalus piscator by Loraine Yeatts.
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Close up of Astragalus piscator by Loraine Yeatts.
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Close up of Astragalus piscator by Peggy Lyon.
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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: Astragalus piscator is a short-lived perennial, with 4-10 lavender or pale lilac flowers on leafless, or mostly leafless stems. Stems are erect when in flower, and often spread out at the base of the leaves when in fruit. The foliage is covered with appressed, dolabriform hairs and is yellowish-green on top and gray-green below. Leaves are pinnately compound with 5-11 leaflets. Pods are somewhat laterally compressed and densely strigose (Spackman et al. 1997, Ackerfield 2015).

Look Alikes: Astragalus musiniensis is similar in appearance but has dorsiventrally compressed pods. Astragalus chamaeleuce also has similar pods but they lack the prominent dorsal structure and elliptic cross section of A. piscator (Spackman et al. 1997). Astragalus piscator is related to A. chamaeleuce, A. musiniensis, and A. amphioxis. It differs from the first two in having chartaceous, not alveolate-pithy pod walls, and differs from the third in flower color which is pale lilac as opposed to vivid pink. The habit and shape of its leaflets suggests A. musiniensis (Cronquist 1989). 

Phenology: Flowers late April to early June (Colorado Natural Heritage Program 2012, Ackerfield 2015).

[+] Habitat

Habitat of Astragalus piscator by Susan Panjabi.
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Habitat of Astragalus piscator by Loraine Yeatts.
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Habitat of Astragalus piscator by Peggy Lyon.
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In Colorado, Astragalus piscator appears to be associated with the Cutler Formation (Colorado Natural Heritage Program 2015), in sandy, sometimes gypsiferous soils of valley benches and gullied foothills (Spackman et al. 1997).  Associated plant community: Juniperus osteosperma. Additional associated plant species: Artemisia tridentata,Coleogyne ramosissima, Atriplex canescens, A. confertifolia, A. gardneri, Sarcobatus vermiculatus, Penstemon utahensis, Castilleja chromosa, C. scabrida, Physaria acutifolia, Cymopteris fendleri, Lepidium lasiocarpum,  Arabis pulchra, Cryptantha gracilis,  Bouteloua gracilis, Allium macropetalum, Erioneuron pulchellum, Townsendia incana, Oryzopsis hymenoides, Chrysothamnus viscidiflorus, Eriogonum inflatum, Astragalus lentiginosus, Oxytropis sericea, Astragalus flexuosus, Stephanomeria tenuifolia, Eriogonum corymbosum, Haplopappus nuttallii, Cryptantha fulvocanescens, Lepidium lasiocarpum, Cymopterus acaulis, Androstephium breviflorum, Townsendia incana, and Astragalus lonchocarpus. 

Elevation Range: 4,511 - 5,581 feet (1,375 - 1,701 meters)

[+] Distribution

Distribution of Astragalus piscator in Colorado according to mapped land ownership/management boundaries (CNHP 2015, COMaP v9).
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Distribution of Astragalus piscator in Colorado.
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Colorado endemic: No
Global range: Occurs in Arizona, Utah (San Juan, Grand, and Wayne counties), and Colorado (Mesa County).
State range: Known from four occurrences in Mesa County in Colorado. Also known from Utah.

[+] Threats and Management Issues

Summary results of an analysis of the status of Astragalus piscator based on several ranking factors. This species was concluded to be “Moderately Conserved”. From Rondeau et al. 2011.
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The primary threat at this time is considered to be roads (Rondeau et al. 2011). The Colorado occurrences are partially within the BLM Palisade Wilderness Study Area, and the Palisade Area of Critical Environmental Concern (ACEC). However, the area is heavily grazed and includes many exotic species (e.g., cheatgrass and Russian knapweed). A portion of this occurrence is also near the Gateway Community Center. Motorized recreation poses a threat at this location.

[+] References

    • Ackerfield, J. 2015. Flora of Colorado. Brit Press, Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.
    • Albee, B.J., L.M. Shultz, and S. Goodrich. 1988. Atlas of the vascular plants of Utah. Utah Museum Natural History Occasional Publication 7, Salt Lake City, Utah. 670 pp.
    • Barneby, R. C., and S. L. Welsh. 1986. New species of Astragalus (Leguminosae) from southeastern Utah. Great Basin Naturalist 45(3):551-552.
    • 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.
    • Baskin, C.C., J.M. Baskin and E. Quarterman. 1972. Observations on the ecology of Astragalus tennesseensis. Amer. Midl. Natur. 88(1): 167-182.
    • Beardsley, M. and D. A. Steingraeber. 2013. Population dynamics, rarity and risk of extirpation for populations of Mimulus gemmiparus (budding monkeyflower) on National Forests of Colorado. A research report submitted to the USFS Forest Service. Arapaho and Roosevelt National Forets and Pawnee National Grassland. pp 17. Accessed online on May 11 at: http://www.r5.fs.fed.us/wildflowers/Rare_Plants/profiles/Critically_Imperiled/mimulus_gemmiparus/ documents/USFS_MimulusStatusReport2013.pdf
    • Cronquist A. 1989. Intermountain Flora Vascular Plants of the Intermountain West, USA. Vol. 3, Part B. New York Botanical Garden, Bronx, NY.
    • Green, T.W. and G.E. Bohart. 1975. The pollination ecology of Astragalus cibarius and Astragalus utahensis (Leguminosae). Amer. J. Bot. 62(4): 370-386.
    • 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.
    • NatureServe. 2015. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. (Accessed: 2015).
    • 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.
    • Panjabi, S., B. Neely and P. Lyon. 2011. Preliminary Conservation Action Plan for Rare Plants in the Gateway Priority Action Areas. Prepared by The Nature Conservancy and the Colorado Natural Heritage Program. Unpublished report prepared for the National Fish and Wildlife Foundation. 29 pp.
    • Rondeau, R., K. Decker, J. Handwerk, J. Siemers, L. Grunau, and C. Pague. 2011. The state of Colorado's biodiversity 2011. Prepared for The Nature Conservancy. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado.
    • 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. 2015. The PLANTS Database (http://plants.usda.gov). 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.
    • 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.

Last Updated

2015-06-08