Unamia alba
Author: (Nutt.) Nesom

Prairie goldenrod

Asteraceae (Sunflower Family)

Close up of Unamia alba by Susan Spackman Panjabi.
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Close up of Unamia alba by Delia Malone.
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Close up of Unamia alba by Crystal Strouse.
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Close up of Unamia alba by Crystal Strouse.
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Taxonomic Comments

=Oligoneuron album (Kartesz 1999).
=Solidago ptarmicoides (Flora of North America 2006, Ackerfield 2015).

Ranks and Status

Global rank: G5
State rank: S1
Federal protection status: None
State protection status: None

[+] Description and Phenology

Unamia alba from the USDA-NRCS PLANTS Database, Britton and Brown 1913.
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Unamia alba by Janet Wingate.
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General description: Prairie goldenrod has stems that are 1-7 dm high and clustered on a woody-thickened, branched rootcrown. The narrowly lance-shaped leaves near the base of the plant have entire margins and are petiolate and up to 20 cm long, while those on the upper stem are shorter, strap-shaped, and lacking petioles. Foliage is glabrous to slightly roughened. The 3-60 flower heads are borne in an open, flat-topped inflorescence. The glabrous, overlapping involucral bracts of each head are 5-7 mm long, each with a greenish apex and a prominent, thickened midrib. The 10-25 rayflowers are white and 5-9 mm long, and the numerous disk flowers are white. The achene is glabrous and has a pappus of bristles that are thickened toward the top.

Look Alikes: Differs from Solidago species in having larger inflorescences and white to pale yellow flowers rather than yellow ones. Distinguished from white flowered, linear- lanceolate leaved Aster species (A. junciformis, A. hesperium, A. porteri, and A. ascendens = Virgulaster ascendens) in having a prominent midrib on the phyllaries and at least some of the pappus bristles enlarged at the apex (Spackman et al. 1997).

Phenology: In Colorado, this species flowers July through September (Ackerfield 2015).

[+] Herbarium Photos

Images of Unamia alba housed at the Colorado State University Herbarium.

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[+] Habitat

Habitat of Unamia alba by Delia Malone.
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Habitat of Unamia alba by Crystal Stouse.
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In Colorado, this species is found in wet to dry, open prairies, forest clearings, or montane meadows (Spackman et al. 1997, Ackerfield 2015). Associated plant species include Pinus ponderosa, Festuca arizonica, Muhlenbergia montana, Danthonia parryi, Cercocarpus montana, Koeleria macrantha, Castilleja integra, Orthocarpus luteus, Bahia dissecta, Heterotheca villosa, Campanula rotundifolia, Allium cernuum, Arenaria fendleri, Antenarria pulcherrima, Besseya plantaginea, Erigeron flagellaris, Frasera speciosaSchizachyrium scoparium and Cirsium flodmanii.

Elevation Range: 5,558 - 9,967 feet (1,694 - 3,038 meters)

[+] Distribution

Distribution of Unamia alba in Colorado according to mapped land ownership/management boundaries (CNHP 2017, COMaP).
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Distribution of Unamia alba in Colorado.
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Colorado endemic: No
Global range: Saskatchewan east through Quebec, south to Colordao, Oklahoma, Arkansas, Georgia and South Carolina (USDA NRCS 2017; Flora of North America 2006).
State range: In Colorado, this species is known from El Paso, Larimer, Park and Teller counties.

[+] Threats and Management Issues

Noted threats include oil and gas developments, fragmentation from road and trail building, weed treatments, pipeline development, industrial and municipal water withdrawals (Colorado Natural Heritage Program occurrence records as of 2017). Colorado climate scenarios for 2050 suggest temperature will increase by 3-7 F and precipitation may decrease or increase. The impact to any given rare plant habitat is likely to vary. Long-term monitoring that includes weather and soil moisture data is critical to understanding climate impacts.

[+] References

    • Britton, N. L. and A. Brown. 1913. An Illustrated Flora of the Northern United States and Canada. 3 vol. Dover Publications, Inc., N. Y. 2052 pp.
    • Colorado Native Plant Society. 1997. Rare Plants of Colorado, second edition. Falcon Press Publ., Helena, MT.
    • Colorado Natural Heritage Program and the Geospatial Centroid. 2017. The Colorado Ownership and Protection Map (COMaP). Colorado State University, Ft. Collins, CO.
    • Flora of North America Editorial Committee. 2006. Flora of North America North of Mexico. Vol. 20. Magnoliophyta: Asteridae, part 7: Asteraceae, part 2. Oxford Univ. Press, New York. xxii + 666 pp.
    • Great Plains Flora Association. 1986. Flora of the Great Plains. University Press of Kansas, Lawrence, KS. 1402 pp.
    • 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.
    • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.
    • Rydberg, P.A. 1906. Flora of Colorado. Bull. 100, Colorado Agricultural Experiment Station, Fort Collins, Colorado. 488pp.
    • 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, Natural Resources Conservation Service, PLANTS Database [USDA PLANTS]. http://plants.usda.gov/. Accessed 2017.
    • Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora, Eastern Slope, A Field Guide to the Vascular Plants, Fourth Edition. Boulder, Colorado. 555 pp.

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