Ipomopsis aggregata ssp. weberi
Author: V. Grant & Wilken

Rabbit Ears gilia

Polemoniaceae (Phlox Family)

Close up of Ipomopsis aggregata ssp. weberi by David Anderson
Click image to enlarge.

Close up of Ipomopsis aggregata ssp. weberi by David Anderson
Click image to enlarge.

Taxonomic Comments

Ackerfield (2012) does not recognize this subspecies and includes it with I. aggregata ssp. attenuata.

Ranks and Status

Global rank: G5T2
State rank: S2
Federal protection status: USFS Sensitive
State protection status: None

[+] Description and Phenology

Please see 1997 profile, and artwork in RARE and Imperiled Plants of Colorado (Rocky Mountain Society of Botanical Artists 2009).

General description: Ipomopsis aggregata ssp. weberi is a herbaceous perennial. It has a taproot, a soft woody base, and one to several erect stems. The stems are 15 to 60 cm tall. The leaves are lobed, relatively large, and well-developed at the base of the plant. Leaves on the stems are much smaller. The flowers are arranged in a panicle on the upper parts of the stem. The flowers are particularly closely spaced, and the flowering stem looks congested. The congested arrangement of the flowers is a distinctive characteristic. The flowers are white, less often pinkish, and fragrant smelling. The calyx lobes are 3 mm long. The corolla has a long slender tube that abruptly flares into a circular limb that looks trumpet-shaped. The tube is slender, 10 to 22 mm long, circular in cross-section, approximately 1 mm wide at the base, and has a narrow orifice between 1 to 2 mm in diameter. Anthers are usually at the orifice or sometimes exerted (Grant and Wilken 1986, Ladyman 2004). 

Look Alikes: Ipomopsis aggregata ssp. attenuata has a more open corolla tube (1 mm wide at base flaring to 2-3 mm at orifice), and pink to red flowers. These species intergrade where their ranges overlap (Grant and Wilken 1986, Spackman et al. 1997).

Phenology: Flowers in July (Colorado Natural Heritage Program 2012).

[+] Habitat

Habitat of Ipomopsis aggregata ssp. weberi by David Anderson
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Ipomopsis aggregata ssp. weberi is found in openings in coniferous forests (Grant and Wilken 1986, Spackman et al. 1997). This species occurs with other herbaceous perennials, and is most commonly associated with sagebrush (Artemisia species) and less often with snowberry, brushy serviceberry, rabbitbrush, and chokecherry (Ladyman 2004). It has also been found in subalpine fir/Englemann spruce/willow habitat and subalpine fir/alder habitat. Ipomopsis aggregata ssp. weberi grows on ridge tops, in mountain meadows, and on variable slopes, ranging from 0 to 35 percent. Plants have most often been reported from slopes with west, south, and east aspects. Ipomopsis aggregata ssp. weberi typically grows in rocky, gravelly soils of a sandy and coarse texture that are derived from a variety of geological formations (Ladyman 2004).

Elevation Range: 6,634 - 10,567 feet (2,022 - 3,221 meters)

[+] Distribution

Distribution of Ipomopsis aggregata ssp. weberi in Colorado
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Colorado endemic: No
Global range: Regional endemic of northern Idaho, south-central Wyoming, and north-central Colorado.

State range: Known from Grand, Jackson, and Routt counties in Colorado. Estimated range in Colorado is 2631 square kilometers (1016 square miles), calculated in GIS by drawing a minimum convex polygon around the known occurrences (calculated by the Colorado Natural Heritage Program in 2008). Also known from Idaho and Wyoming.

[+] Threats and Management Issues

Summary results of an analysis of the status of Ipomopsis aggregata ssp. weberi 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 recreational uses of its habitat (Rondeau et al. 2011). It is not known if all of the occurrences are or are not threatened by these activities. Concern about the viability of Ipomopsis aggregata ssp. weberi is a result of its limited geographic range and the potential impacts of the multiple uses of its habitat. Recreational activities, such as mountain bike riding, snowmobiling, hiking, horseback riding, and development activities associated with recreation and urbanization, such as campsite development and road building. As the human population grows in areas within easy access to I. aggregata ssp. weberi habitat and as recreational use increases, the impacts may become substantially more significant. At current levels, grazing and trampling by native and non-native ungulates may also have an impact, especially on smaller colonies. Activities associated with resource extraction are not currently perceived to be a threat although individual occurrences may have been impacted in the past. Invasive weeds are likely a threat to the long-term sustainability of some occurrences. If other subspecies or races of I. aggregata are introduced, for example in revegetation seed mixes, both hybridization and outbreeding depression are potential threats (Ladyman 2004). Further, one occurrence indicates that future logging projects may impact the site. Several of the occurrences are roadside but do continue into natural habitat (Colorado Natural Heritage Program).

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Grant, V., and D. H. Wilken. 1986. Taxonomy of the Ipomopsis aggregata group (Polemoniaceae). Botanical Gazette 147(3):359-371.
    • 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.
    • Ladyman, J.R.A. 2004. Ipomopsis aggregata (Pursh) V. Grant ssp. weberi V. Grant and Wilken (scarlet gilia): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/ipomopsisaggregatasspweberi.pdf.
    • 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.
    • Rocky Mountain Society of Botanical Artists. 2009. RARE Imperiled Plants of Colorado, a traveling art exhibition. Exhibition catalogue developed by the Denver Botanic Gardens and Steamboat Art Museum.
    • 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. 2013. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.
    • 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.
    • 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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