Draba weberi
Author: Price & Rollins

Weber's draba

Brassicaceae (Mustard Family)

Close up of Draba weberi by Jill Handwerk
Click image to enlarge.

Close up of Draba weberi by Steve Olson
Click image to enlarge.
Close up of Draba weberi by Steve Olson
Click image to enlarge.
Close up of Draba weberi by Bernadette Kuhn
Click image to enlarge.

Ranks and Status

Global rank: G1
State rank: S1
Federal protection status: USFS Sensitive
State protection status: None

[+] Description and Phenology

Artwork in progress by Vicky MacWilliam. Please also see 1997 profile.

General description: Draba weberi is a perennial, tufted herb growing 2 to 10 cm (0.75 to 4.0 inches) tall. Its unbranched stems are sparsely hairy with simple or branched hairs (FNA 2010). There may be 1 to 3 linear-oblanceolate stem leaves that are pubescent below. These are 4 to 15 mm (0.16 to 0.6 inch) long (FNA 2010). The basal leaves are similar. Flowers are borne on pedicels 2 to 6mm (0.08 to 0.24 inch) long, having hairs similar to those on the leaves. The yellow petals are 3 to 4 mm (0.12 to 0.18 inch) long, and 1.2 to 1.8 mm wide (0.05 to 0.07 inch) wide. These are clawed (having a narrow stalk at the base). The fruits are ovate 4 to 8 mm (0.16 to 0.31 inch) long and 2 to 3 mm (0.08 to 0.12 inch) wide.  (Spackman et al. 1997, pers. com. Olson 2012).  

Look Alikes: Draba weberi is an apomictic species allied to three other yellow-flowered Draba species with overlapping ranges: D. exunguiculata, D. grayana, and D. streptobrachia. Field identification is challenging. Draba weberi can be distinguished by ovate fruits, clawed petals, and sessile, 2-4 rayed trichomes with untwisted rays often appressed to leaf and stem surfaces (Flora of North America 2010). Although it often occurs in wetter habitats, it has also been documented growing in dry, upland habitats (Colorado Natural Heritage Program 2014).

Phenology: Draba weberi flowers from late June to late July (Rollins 1993, Flora of North America 1993+, Decker 2006).

[+] Habitat

Habitat of Draba weberi by Jill Handwerk
Click image to enlarge.

Habitat of Draba weberi by Susan Spackman Panjabi
Click image to enlarge.

Draba weberi is found most often in rocky crevices along streams near timberline, usually associated with spruce-fir and willow plant communities.  It is occasionally found in drier sites on margins of alpine lakes.  Associated species include Mertensia ciliata, Smelowskia calycina, Oxyria digyna, Erigeron pinnatisectus, Cystopteris fragilis, Draba streptobrachia, Rhodiola integrifolia, Potentilla fruticosa, Cilaria austromontana, and a variety of mosses and lichens (Colorado Natural Heritage Program 2013).

Elevation Range: 11,122 - 11,165 feet (3,390 - 3,403 meters)

[+] Distribution

Distribution of Draba weberi in Colorado.
Click image to enlarge.

Colorado endemic: Yes
Global range: Known from the type locality in Summit County, Colorado and three recently discovered sites in both Summit and Park County, Colorado.

[+] Threats and Management Issues

Summary results of an analysis of the status of Draba weberi based on several ranking factors. This species was concluded to be “under conserved”. From Rondeau et al. 2011.
Click image to enlarge.

Hydrologic alterations are considered to be the primary threat to the species at this time (CNHP 2012). At the type locality, the population depends on water flowing from an outflow pipe below a dam that enters a relatively natural creek bed; land is owned by a municipal water company (Decker 2006). The remaining occurrences all occur along the banks of upper subalpine lakes or the splash zone of streams fed by snowmelt. One exception occurs where plants have been found growing in moist duff under spruce-fir trees. The species is also threatened by recreation and trampling; two of the occurrences are along hiking trail and areas that are easily accessed by climbers, hikers, and backcountry skiers (CNHP 2012; Decker 2006). Other threats include road and dam construction and maintenance; disturbance by mining (many claims in area, one claim in upper valley with sporadic activity); spread of exotic species (no exotics reported from drainage, but Matricaria perforata reported nearby on the North Star Mountain road); collecting (for rock-gardens), and global climate change (Decker 2006).

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Flora of North America Editorial Committee. 2010. Flora of North America North of Mexico. Vol. 7. Magnoliophyta: Salicaceae to Brassicaceae. Oxford University Press, New York. xxii + 797 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.
    • 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.
    • Price, R. A. and R. C. Rollins. 1991. New taxa of Draba (Cruciferae) from California, Nevada, and Colorado. Harvard Papers in Botany 3: 71-77.
    • Rollins, R.C. 1993. The Cruciferae of continental North America: Systematics of the mustard family from the Arctic to Panama. Stanford Univ. Press, Stanford, California. 976 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.
    • U.S. Fish and Wildlife Service (USFWS). 2009. Endangered and Threatened Wildlife and Plants; Partial 90-Day Finding on a Petition To List 206 Species in the Midwest and Western United States as Threatened or Endangered With Critical Habitat. Federal Register 74(158): 41649-41662. 18 August 2009.
    • U.S. Forest Service (USFS). 2003. Response to species-specific comments on draft region 2 sensitive plant list. August 13, 2003. U.S. Forest Service, Rocky Mountain Region, Golden, Colorado.
    • 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