Physaria scrotiformis
Author: O'Kane


West silver bladderpod


Brassicaceae (Mustard Family)

Close up of Physaria scrotiformis by Steve O'Kane
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Close up of Physaria scrotiformis by Steve O'Kane
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Close up of Physaria scrotiformis. Photo ŠAl Schneider, www.swcoloradowildflowers.com.
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Taxonomic Comments

Described in 2007 (O'Kane 2007).

Ranks and Status

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

[+] Description and Phenology

Physaria scrotiformis: by Karen Boggs Cleaver.
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General description: Physaria scrotiformis is a long-lived perennial from a simple or sparsely branched underground caudex. While the fruit are rather distinctive (hence, the specific epithet), the flowers have not been seen! Plants are silvery-gray-green to silvery-purplish, the silver color due to a dense covering of trichomes. Stems are 0.8 to 3 cm long, unbranched, purplish, arising lateral (beneath) the erect or ascending tuft of basal leaves, prostrate to slightly decumbent, from stem tip to stem tip plants up to 10 cm, but typically less than 5.5 cm in diameter. Basal leaves are entire, oblanceolate, elliptic or rhombic, mostly flat, sometimes somewhat folded, attenuate at base and tapering to a slightly winged petiole. Apex rounded to rounded-acute, including the petiole, encrusted with trichomes. Cauline leaves are entire, elliptic to oblanceolate, short-petiolate to essentially entire, 3 to 7 per stem. Infructescence, not elongating appreciably, is a raceme with 3 to 7, more or less crowded fruits, these on straight, ascending pedicels 1.8 to 3.4 mm long. Silicles on stipes 0.2 to 0.5 mm long, ovoid to obpyriform, slightly but obviously didymous (especially in living material), apex rounded, flattened, or even slightly emarginate; base rounded-obtuse; wider than long; 3 to 4.5 mm long and 3.7 to 5 mm wide, the valves inflated and a little wider than the replum; valves glabrous within, the exterior with scattered tricomes; becoming purplish or greenish-purple at maturity; replum entire or medially small-perforate, obovate to rounded-obdeltoid, rounded to obtuse or truncate at the apex (O'Kane 2007).

Look Alikes: Not likely to be confused with other taxa in this habitat in this part of Colorado.

Phenology: Fruiting in July (O'Kane 2007, Colorado Natural Heritage Program 2012).

[+] Herbarium Photos

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

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[+] Habitat

Habitat of Physaria scrotiformis by Steve O'Kane
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Habitat of Physaria scrotiformis by Steve O'Kane
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Grows on windswept, nearly barren exposures of Leadville limestone in a matrix of Picea engelmannii islands and tundra. Associates on the nearly barren spots where the species occurs include Minuartia obtusiloba, Zigadenus elegans, Castilleja haydenii, Pseudocymopterus montana, Poa alpina, Hymenoxys grandiflora, Allium geyeri, Townsendia rothrockii and Trisetum spicatum. The plants grow in shallow soil between grey and tan-grey limestone cobbles (O'Kane 2007).

Elevation Range: 11,555 - 11,834 feet (3,522 - 3,607 meters)

[+] Distribution

Distribution of Physaria scrotiformis in Colorado according to mapped land ownership/management boundaries (CNHP 2012, COMaP v9 ).
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Distribution of Physaria scrotiformis in Colorado
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Colorado endemic: Yes
Global range: Endemic to Colorado. Upper sub-alpine-lower alpine zone of the San Juan Mountains in La Plata County, Colorado (O'Kane 2007).

[+] Threats and Management Issues

Although rare, this new species is probably not currently endangered by direct human activities because the whole of its habitat is contained within the Weminuche Wilderness Area. With no appropriate contiguous or nearby limestone substrate at higher elevations to allow for population migration, however, global warming could present a real threat to the species, especially if vegetation types at lower elevations were to invade the inhabited sites (O'Kane 2007).

[+] References

    • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.
    • Colorado Natural Heritage Program. 2005. The Second Annual Colorado Rare Plant Symposium: G1 Plants of Colorado. Symposium Minutes. Available on-line http://www.cnhp.colostate.edu/teams/botany.asp#symposia.
    • Colorado Natural Heritage Program. 2010. The Seventh Annual Colorado Rare Plant Symposium: G1 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.
    • Heil, K.D., S.L. O'Kane Jr., L.M. Reeves, and A. Clifford, 2013. Flora of the Four Corners Region, Vascular Plants of the San Juan River Drainage; Arizona, Colorado, New Mexico, and Utah. Missouri Botanical Garden Press, St. Louis, Missouri. 1098 pp.
    • 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.
    • O'Kane, S.L., Jr. 2007. Physaria scrotiformis (Brassicaceae), a new high-elevation species from southwestern Colorado and new combinations in Physaria. Novon 17(3): 376-382.
    • Schneider, A. 2013. Wildflowers, Ferns, and Trees of the Four Corners Regions of Colorado, New Mexico, Arizona, and Utah. Accessed on-line at http://www.swcoloradowildflowers.com.
    • 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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