Boechera crandallii
Author: B.L. Robins.


Crandall's rock-cress


Brassicaceae (Mustard Family)

Close up of Boechera crandallii by Barry Johnston
Click image to enlarge.

Taxonomic Comments

=Arabis crandallii (USDA NRCS 2012).

Ranks and Status

Global rank: G2
State rank: S2
Federal protection status: BLM Sensitive
State protection status: None

[+] Description and Phenology

Boechera crandallii: no artwork available

General description: Perennial with a branched caudex, stems slender and numerous, erect, rarely branched, densly pubescent to sparsely so, 1.5-4 dm high. Basal leaves are numerous, entire, occassionally somewhat toothed, oblanceolate in shape and  pubescent, 1.5-3 cm long. Upper leaves are oblong to lanceolate, hairy and 8-15 mm long. Flower petals are white-pinkish 5-7 mm long and 2-3 mm wide. Fruits (siliques) are smooth, slender pods 3-6 cm long, with constritions between the seeds. Seeds are round to slightly oblong, wingless to very narrowly winged (Ladyman 2005, Rollins 1993).

Look Alikes: Boechera pallidifolia has broader siliques, purplish flowers, and is more densely caespitose (B. crandallii is caespitose but with few stems; Ladyman 2005, Weber and Wittmann 2012).

Phenology: Flowers from May through June (Rollins 1993, Colorado Natural Heritage Program 2012).

[+] Herbarium Photos

Images of Boechera crandallii housed at the Colorado State University Herbarium.

Click image to enlarge.

[+] Habitat

Habitat of Boechera crandallii by Barry Johnston
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This plant grows in limestone chip-rock and stony areas, often among sagebrush, ridges, and steep hill slopes (Rollins 1993). It is commonly growing with Boechera pallidiflora (Weber and Wittmann 2012). According to Rollins (1993), Boechera crandallii and B. pallidifolia grow in the same area but colonize different habitats; B. crandallii grows in more open, sometimes windswept places whereas B. pallidifolia grows in relatively protected places frequently associated with sagebrush (Ladyman 2005). Associated species include Pinus ponderosa, Cercocarpus montanus, Ribes cereum, Artemisia vaseyana, Ribes cereum, and Purshia tridentata (Colorado Natural Heritage Program 2012).

Elevation Range: 8,176 - 10,607 feet (2,492 - 3,233 meters)

[+] Distribution

Distribution of Boechera crandallii in Colorado according to mapped land ownership/management boundaries (CNHP 2012, COMaP v9 ).
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Distribution of Boechera crandallii in Colorado: please see county list under State Range.

Colorado endemic: No
Global range: Regional endemic of central Colorado, Gunnison, Park, and Chaffee counties, and southern Wyoming, Carbon and Sweetwater counties (USDA NRCS 2012).
State range: Ladyman (2005) reports this species from eight counties in west-central Colorado (Chaffee, Delta, Gunnison, Montrose, Rio Blanco, Grand, Park, and Saguache). The PLANTS database (USDA NRCS 2012) shows only three counties, Park, Chaffee, and Gunnison.

[+] Threats and Management Issues

The primary threat at this time is considered to be roads (Rondeau et al. 2011). It is not known if all of the occurrences are or are not threatened by these activities. Habitat loss is another substantial threat to this species. Extrinsic factors such as resource extraction, activities associated with recreation, road development, and grazing are the primary range-wide threats to Arabis (Boechera) crandallii. Invasion of habitat by non-native species is also a source of concern. The species is likely only moderately competitive and may be out-competed by non-native plant species. Occurrences on land managed by the USDA Forest Service Region 2 are likely to be most vulnerable to invasive weeds encroaching in their habitat, activities associated with recreation, campground and road improvement, and livestock grazing. Details of imminent threats to specific occurrences are unavailable. Long-term population sustainability may be vulnerable to declines in pollinator populations. Actions that substantially reduce the numbers of individuals within a population may exacerbate the potential for inbreeding depression that would reduce population viability (Ladyman 2005).

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Colorado Natural Heritage Program. 2012. Biodiversity Tracking and Conservation System. Colorado State University, Fort Collins, CO.
    • Dorn, R.D. 1992. Vascular plants of Wyoming, 2nd edition. Mountain West Publishing, Cheyenne, Wyoming.
    • Fertig, W. 2000. August 18-last update. Arabis crandallii State Species Abstract. Online. Available: http://uwadmnweb.uwyo.edu/WYNDD/PDF_files/Plant_Summaries/B/Boechera%20crandallii.pdf. Accessed 2003, April 17.
    • Flora of North America Editorial Committee, ed. (FNA). 1993+. Flora of North America North of Mexico. Oxford Univ. Press, New York, Oxford.
    • 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.A.R. 2005. Boechera crandallii (B.L. Robinson) W.A. Weber (Crandall's rockcress): a technical conservation assessment. USDA Forest Service, Rocky Mountain Region. Online. Available: http://www.fs.fed.us/r2/projects/scp/assessments/boecheracrandallii.pdf (Accessed 2006).
    • Lavender, A.E., M.M. Fink, S.E. Linn, D.M. Theobald. 2011. Colorado Ownership, Management, and Protection v9 Database. Colorado Natural Heritage Program and Geospatial Centroid, Colorado State University, Fort Collins, CO. (30 September).
    • 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.
    • 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.
    • Rydberg, P.A. 1906. Flora of Colorado. Agricultural Experiment Station of the Colorado Agricultural College, Fort Collins.
    • 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

2013-02-13