Astragalus schmolliae
Author: C.L. Porter


Chapin Mesa milkvetch


Fabaceae (Pea Family)

Close up of Astragalus schmolliae by George SanMiguel
Click image to enlarge.

Close up of Astragalus schmolliae by Bernadette Kuhn
Click image to enlarge.
Close up of Astragalus schmolliae by Bernadette Kuhn
Click image to enlarge.

Ranks and Status

Global rank: G1
State rank: S1
Federal protection status: USFWS Candidate
State protection status: None

[+] Description and Phenology

Please see artwork on 1997 profile

General description: Herbaceous perennial plants, 4-6 dm tall. Leaves are composed of 11-20 linear leaflets. Uppermost leaflet is jointed to the the rachis. Flowers are white, about 2 cm long, and have black hairs on the calyx. Pods are about 4 cm in length, strigose, curved downward, and dorsiventrally compressed (Spackman et al. 1997).

Look Alikes: Astragalus schmolliae was possibly derived from a cross of A. lonchocarpus and A. scopulorum (Weber and Whittmann 1987). Astragalus lonchocarpus differs from A. schmolliae in having glabrous pods, and 1-9 leaflets with the terminal leaflet not jointed to the rachis. Astragalus scopulorum has truly connate stipules and sharply trigonous, laterally compressed pods (Spackman et al. 1997).

Phenology: Flowers in May and fruits in June (Colorado Natural Heritage Program 2012).

[+] Habitat

Habitat of Astragalus schmolliae by George SanMiguel
Click image to enlarge.

Habitat of Astragalus schmolliae by Bernadette Kuhn
Click image to enlarge.

Sandy and gravelly flats and terraces, among junipers and pinyon pines, on sandstone (Spackman et al. 1997).  Fire is a natural component of the habitat for this species.  Associated taxa include: Purshia tridentata, Amelanchier utahensis, Poa fendleriana, Achnatherum hymenoides, Penstemon linarioides, Quercus gambelii, Solidago petrodora, Opuntia polyacantha, Yucca baccata, Astragalus wingatanus, Lupinus amophilius, Eriogonum racemosum, Chrysopsis villosa, and Polygonum sawatchense. 


Sandy and gravelly flats and terraces, among junipers and pinyon pines, on sandstone (Spackman <i>et al. </i>1997). Fire is a natural component of the habitat for this species. Associated taxa include: <i>Purshia tridentata, Amelanchier utahensis, Poa fendleriana, Achnatherum hymenoides, Penstemon linarioides, Quercus gambelii, Solidago petrodora, Opuntia polyacantha, Yucca baccata, Astragalus wingatanus, Lupinus amophilius, Eriogonum racemosum, Chrysopsis villosa, and Polygonum sawatchense.

Elevation Range: 5,764 - 7,424 feet (1,757 - 2,263 meters)

[+] Distribution

Distribution of Astragalus schmolliae in Colorado.
Click image to enlarge.

Colorado endemic: Yes
Global range: Endemic to Montezuma County, Colorado. It is found in the vicinity of Chapin Mesa extending south approximately 6 miles into the Ute Mountain Ute Reservation. Estimated range is 18 square kilometers, calculated in 2008 by the Colorado Natural Heritage Program in GIS by drawing a minimum convex polygon around the known occurrences. Imprecisely reported occurrences are not included.

[+] Threats and Management Issues

Summary results of an analysis of the status of Astragalus schmolliae based on several ranking factors. This species was concluded to be "moderately conserved”. From Rondeau et al. 2011.
Click image to enlarge.

The primary threat to the species is the invasion of weeds into burned areas which are occupied by Astragalus schmolliae. Musk thistle (Carduus nutans) is particularly invasive in burned areas of southern Mesa Verde National Park (MVNP), and has been observed invading areas occupied by A. schmolliae. Cheatgrass (Bromus tectorum) is also invading burned areas occupied by A. schmolliae. Visitor impacts to A. schmolliae within MVNP are localized and minimal, limited to trampling of an occasional plant growing adjacent to a trail or road (Anderson 2004). Outside of MVNP boundaries the threats are grazing and road construction (O'Kane 1988).

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Anderson, D.G. 2004. Final Report: Population Status Survey of Schmoll's Milkvetch (Astragalus schmolliae Porter). Prepared for the National Park Service, Mesa Verde National Park. The Colorado Natural Heritage Program, Fort Collins, CO.
    • Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.
    • Colorado Native Plant Society. 1989. Rare plants of Colorado. Rocky Mountain Nature Association, Colorado Native Plant Society, Estes Park, Colorado. 73 pp.
    • Colyer, M. 1994. Personal Communication 4/2/94. Natural Resources, Mesa Verde National Park, Colorado.
    • 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.
    • O'Kane, S. L. 1988. Colorado's Rare Flora. Great Basin Naturalist. 48(4):434-484.
    • O'Kane, S.L. 1988. Colorado's rare flora. Great Basin Naturalist 48(4): 434-484.
    • Peterson, J. S., B.C. Johnston, and W. Harmon. 1981. Astragalus microcymbus status report of 3 March 1981.
    • 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.

Last Updated

2014-11-20