Astragalus linifolius
Author: Osterhout

Grand Junction milkvetch

Fabaceae (Pea Family)

Close up of Astragalus linifolius by Lori Brummer.
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Close up of Astragalus linifolius by Lori Brummer.
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Close up of Astragalus linifolius by Lori Brummer.
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Close up of Astragalus linifolius by Peggy Lyon.
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Taxonomic Comments

Very close morphologically to A. rafaelensis, basically only differing in the erect fruit. Additionally, A. linifolius is found east of the Uncompahgre Plateau, while A. rafaelensis is found west of it (Ackerfield 2015).

Ranks and Status

Global rank: G3Q
State rank: S3
Federal protection status: BLM Sensitive
State protection status: None

[+] Description and Phenology

Please see 1997 profile.

General description: Perennials, up to 4 dm in height, multi-branched, plants forming dense clumps, marcescent stems often present. Leaves 4-12 cm long, reduced to a filiform leaf stalk. Flowers white with purple tipped keel in racemes of 7-12 flowers. Pods are glabrous, erect, 1.2-1.5 cm long, and ellipsoid-oblong in shape (Spackman et al. 1997, Ackerfield 2015).

Look Alikes: Looks like A. rafaelensis which occurs in similar habitats in the lower Dolores drainage. However, this species has pendant pods while A. linifolius has erect pods (Ackerfield 2015).

Phenology: Flowering occurs from late May to June, and fruits in early to mid June (Peterson 1983, Spackman et al. 1997, Ackerfield 2015).

[+] Habitat

Habitat of Astragalus linifolius by Lori Brummer.
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Found in rocky soil on dry hillsides (Ackerfield 2015). Many populations occur on the Chinle and Morrison Formations with pinyon-juniper and sagebrush (O'Kane 1988). Often found in drainages and along benches of perennial streams. Associated species include: Cercocarpus montanus, Oryzopsis hymenoides, Heterotheca villosa, Chrysothamnus viscidiflorus, Hymenopappus filifolius, Atriplex confertifolia, Hilaria jamesii, Hymenoxys acaulis, Castilleja linariifolia, Sarcobatus vermiculatus, Bouteloua curtipendula, Opuntia phaeocantha, Gutierrezia sarothrae, Artemisia ludoviciana, Senecio multilobatus, Galium coloradense.

Elevation Range: 4,787 - 7,326 feet (1,459 - 2,233 meters)

[+] Distribution

Distribution of Astragalus linifolius in Colorado according to mapped land ownership/management boundaries (CNHP 2015, COMaP v9).
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Distribution of Astragalus linifolius in Colorado.
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Colorado endemic: Yes
Global range: Colorado endemic from Montrose, Delta and Mesa Counties. Approximately 300 square miles.

[+] Threats and Management Issues

Grazing, invasive weeds, motorized recreation, and insect larvae infestation have been recorded as potential threats.

[+] References

    • Ackerfield, J. 2015. Flora of Colorado. Brit Press, Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.
    • 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.
    • Johnson, Clarence Dan, professor. Northern Arizona University, Dept. of Biological Sciences, box 5640, (602)523-2505.
    • 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.
    • O'Kane, S.L. 1988. Colorado's rare flora. Great Basin Naturalist 48(4): 434-484.
    • Osterhout, G. 1928. Bullentin of the Torrey Botanical Club 55:75.
    • Peterson, J. S. 1983. Field inventory of selected areas of CO Vol. II Plant Species of Special Concern. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.
    • 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.

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