Physaria rollinsii
Author: Mulligan


Rollins' twinpod


Brassicaceae (Mustard Family)

Close up of Physaria rollinsii by Steve O'Kane
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Close up of Physaria rollinsii by Steve O'Kane
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Ranks and Status

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

[+] Description and Phenology

Physaria rollinsii by Ilgvar Steins from: Gerald A. Mulligan, Two new species of Physaria in Colorado, Canadian Journal of Botany, 1966, vol 44 (12), page 1664. © Canadian Science Publishing or its licensors
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General description: Physaria rollinsii is a small, compact, clump-forming perennial with silvery pubescence and bright yellow flowers. Stems are several from the base, decumbent, and 0.5-1 dm long. Basal leaves form a small rosette, and the leaf blades are usually oblanceolate or broader, and margins entire or with 1 or 2 broad teeth. Cauline leaves are oblanceolate with margins entire. Racemes are congested, and elongate moderately in fruit. Fruits are erect, arranged in pairs, suborbicular, and inflated; replum obovate to oblong, as wide as or wider than the fruit (FNA 2010).


Look Alikes: Physaria rollinsii can be distinguished from other Physaria species by it's very small size; it's linear-oblanceolate basal leaves, which are entire or with a single broad tooth on each side and less than 4 cm long; and it's relatively low elevation range (Weber and Wittmann 2012).

Phenology: Flowers and fruit May-June (Rollins 1993, Colorado Natural Heritage Program 2012).

[+] Herbarium Photos

Images of Physaria rollinsii housed at the Colorado State University Herbarium.

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[+] Habitat

Habitat of Physaria rollinsii by Scott Smith
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Physaria rollinsii is found in granitic talus, open knolls, limestone chiprock, steep slopes, clay banks, near granite boulders (Rollins 1993), and sagebrush (Weber and Wittmann 2012).  Associated plant species include Opuntia fragilis, Cercocarpus montanus, Phlox longifolia, Artemisia tridentata, Chrysothamnus depressus, Penstemon caespitosus (Colorado Natural Heritage Program 2012).

Elevation Range: 6,624 - 9,088 feet (2,019 - 2,770 meters)

[+] Distribution

Distribution of Physaria rollinsii in Colorado according to mapped land ownership/management boundaries (CNHP 2012, COMaP v9 ).
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Distribution of Physaria rollinsii in Colorado
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Colorado endemic: Yes
Global range: Endemic to Colorado; known from Gunnison and Mesa counties.

[+] Threats and Management Issues

Summary results of an analysis of the status of Physaria rollinsii based on several ranking factors. This species was concluded to be “Weakly Conserved”. From Rondeau et al. 2011.
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Specific threats are not known.

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Colorado Natural Heritage Program. 2008. The Fifth Annual Colorado Rare Plant Symposium: G2 Plants of Colorado. Symposium Minutes. Available on-line http://www.cnhp.colostate.edu/teams/botany.asp#symposia.
    • Colorado Natural Heritage Program. 2012. Biodiversity Tracking and Conservation System. Colorado State University, Fort Collins, CO.
    • Flora of North America Editorial Committee, ed. (FNA). 1993+. Flora of North America North of Mexico. Oxford Univ. Press, New York, Oxford.
    • 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., and the Biota of North America Program (BONAP). 1998. A Synonymized Checklist of the Vascular Flora of the United States, Puerto Rico, and the Virgin Islands. http://plants.usda.gov.
    • 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. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.
    • 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.
    • 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.

Last Updated

2013-02-04