Physaria obcordata - Rollins
Piceance Twinpod
Other English Common Names: Dudley Bluffs Twinpod
Other Common Names: Dudley Bluffs twinpod
Taxonomic Status: Accepted
Related ITIS Name(s): Physaria obcordata Rollins (TSN 195788)
Unique Identifier: ELEMENT_GLOBAL.2.145962
Element Code: PDBRA220H0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Mustard Family
Image 12103

Public Domain

 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Capparales Brassicaceae Physaria
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Concept Reference
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Concept Reference: 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.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Physaria obcordata
Conservation Status
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NatureServe Status

Global Status: G1G2
Global Status Last Reviewed: 20Mar2012
Global Status Last Changed: 19May2008
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G1 - Critically Imperiled
Reasons: A narrow endemic of oil shale barrens in the Piceance Basin of northwestern Colorado. Very locally abundant, with 10 documented occurrences, primarily along 2 adjacent drainages. If the oil shale or associated mineral deposits are mined, the survival of this species would be severely threatened.
Nation: United States
National Status: N1N2

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Colorado (S1S2)

Other Statuses

U.S. Endangered Species Act (USESA): LT: Listed threatened (06Feb1990)
U.S. Fish & Wildlife Service Lead Region: R6 - Rocky Mountain

NatureServe Global Conservation Status Factors

Range Extent Comments: Endemic to Colorado; known from Rio Blanco County only along the Piceance and Yellow Creek drainages and at Clamity Ridge. Estimated range is 574 square kilometers, calculated in GIS by the Colorado Natural Heritage Program in 2008 by drawing a minimum convex polygon around the known occurrences.

Area of Occupancy: 1-25 4-km2 grid cells
Area of Occupancy Comments: The total area occupied by the mapped occurrences is 313 acres (calculated by the Colorado Natural Heritage Program in 2012).

Number of Occurrences: 6 - 20
Number of Occurrences Comments: There are 10 principal occurrences documented in the Colorado Natural Heritage Program database. All of the occurrences are in a restricted geographic area. Several occurrences are within approximately 1-2 km of one another, but have not been combined due to data complexity.

Population Size Comments: Total estimated sum of individuals from the 10 documented occurrences is 34,400.

Viability/Integrity Comments: There are 7 occurrences with an A or B rank.

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Oil and gas development is the primary threat. Mining of oil shale and/or nahcolite solution could impact up to 100% of the occupied habitat. A new nahcolite plant at Yankee Gulch, across from Dudley Bluffs was built in 2000. The lease may extend into Ryan Gulch. Additionally, a new drill pad was observed near Dudley Bluffs in 2000 (CNAP 2000). Other threats include livestock grazing and trampling by wild horses. ORV's can cause severe damage if access is allowed into Physaria obcordata habitat.

Short-term Trend: Unknown
Short-term Trend Comments: Reported to decline in years of drought. Monitoring was begun in 1985 by the BLM and the Colorado Natural Areas Program (CNAP). Monitoring was to occur annually for about the first five years and then on a three year cycle. The purpose was to establish a comparison of density data to establish trends. Baseline and precipitation related trends were established and reported in agency planning documents (Roberts 1992).

Long-term Trend: Unknown
Long-term Trend Comments: Unknown. There is insufficient data to characterize long-term trends.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Endemic to Colorado; known from Rio Blanco County only along the Piceance and Yellow Creek drainages and at Clamity Ridge. Estimated range is 574 square kilometers, calculated in GIS by the Colorado Natural Heritage Program in 2008 by drawing a minimum convex polygon around the known occurrences.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States CO

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CO Rio Blanco (08103)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
14 Upper White (14050005)+, Piceance-Yellow (14050006)+, Lower White (14050007)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A perennial herb with flowering stems, 1.2-1.8 dm tall, arising from a tuft of silvery, erect, basal leaves. Flowers are yellow and bloom in May and June. This species is recognized by its dense, silvery covering of dish-shaped hairs which completely encrust its stems, leaves, and heart-shaped fruits.
General Description: Yellow flowered perennial herb with a stout taproot, about 10-20 cm in height. Rosette leaves are oblanceolate, the margins entire to shallowly sinuate-dentate; cauline leaves are narrowly lanceolate, the margins entire. Entire plant is covered with circular trichomes resembling solder splatters. Fruit are obcordate at maturity (Spackman et al. 1997; Ackerfield 2015).
Technical Description: Perennial herb with stellate hairs covering the leaves, stems and fruits. The flowers are yellow, followed by unique inflated heart-shaped inflated siliques that attach to the stalk at the pointed end.

Terrestrial Habitat(s): Bare rock/talus/scree, Barrens
Habitat Comments: Barren white outcrops and steep slopes exposed by creek downcutting. Restricted to the Parachute Creek Member of the oil shale bearing Green River Formation (Spackman et al. 1997).
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Minimum Criteria for an Occurrence: A natural occurrence of one or more plants.
Separation Barriers: Unsuitable habitat or altered areas; or markedly distinct features on the landscape such as ridges, rivers, or roads.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 2 km
Separation Justification: The rationale for this large a separation distance across suitable but apparently unoccupied habitat is that it is likely additional research will find this habitat to be occupied. It can often be assumed that apparently unconnected occurrences will eventually be found to be more closely connected. No information on mobility of pollen and propagules is available on which to base the separation distance for this species.
Date: 12Aug2003
Author: Jill Handwerk
Population/Occurrence Viability
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Excellent Viability: Size: 5,000 or more individuals (based on available EOR data).
Condition: The occurrence has an excellent likelihood of long-term viability as evidenced by the presence of multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. This occurrence should be in a high-quality site with less than 1% cover of exotic plant species and/or no significant anthropogenic disturbance.
Landscape Context: The occurrence is surrounded by an area that is unfragmented and includes the ecological processes needed to sustain this species. This includes the presence of the appropriate, very specific edaphic requirements of this species, i.e. barren, white shale outcrops derived from the oil-bearing shale of the Green River and Uinta Formations.

Good Viability: Size: 1000-4999 individuals (based on available EOR data).
Condition: The occurrence should have a good likelihood of long-term viability as evidenced by the presence of multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. Anthropogenic disturbance within the occurrence is minimal. If exotic species are present, they comprise less than 10% of the total ground cover.
Landscape Context: The surrounding landscape should contain the ecological processes needed to sustain the occurrence but may be fragmented and/or impacted by humans.

Fair Viability: Size: 20 to 999 individuals (based on available EOR data).
Condition: The occurrence may be less productive than the above situations, but is still viable, with multiple age classes and evidence of flowering and fruiting, indicating that the reproductive mechanisms are intact. The occupied habitat is somewhat degraded; exotic plant species make up between 10-50% of the total ground cover and/or there is a moderate level of anthropogenic disturbance.
Landscape Context: There may be moderate human disturbance, but the ecological processes needed to sustain the species are still intact.

Poor Viability: Size: Less than 20 individuals (based on available EOR data).
Condition: Little or no evidence of successful reproduction is observed (poor seedling recruitment, no flowering or fruiting observed, or poor age class distribution). Exotic plant species make up greater than 50% of the total ground cover, and/or there is a significant level of human disturbance.
Landscape context: The surrounding area is fragmented with many ecological processes no longer intact.

Justification: Large populations in high quality sites ("A" or "B" ranked EOs) are presumed to contain a high degree of genetic variability, to have a low susceptibility to the effects of inbreeding depression, and to be relatively resilient. "D" ranked occurrences have a low probability of long-term persistence due to inbreeding depression, natural stochastic events, and their intrinsic vulnerability to human impacts.
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 20Mar2012
NatureServe Conservation Status Factors Author: Maybury, K. and S. Spackman, rev. CNHP 2003, rev. Neuhaus, K., J. Handwerk, and S. Spackman Panjabi (2006); rev. Handwerk, J. (2011-12)
Element Ecology & Life History Edition Date: 20Nov2014
Element Ecology & Life History Author(s): Bell, J., rev. Susan Panjabi (2014)

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
Help
  • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.


  • Ackerfield, J. 2015. Flora of Colorado. Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.

  • Anderson, J. 1992 c. Draft Recovery Plan for Physaria obcordata and Lesquerella congesta. Unpublished report prepared for the U.S. Fish and Wildlife Service, Grand Junction, Colorado.

  • Colorado Native Plant Society. 1989. Rare plants of Colorado. Rocky Mountain Nature Association, Colorado Native Plant Society, Estes Park, Colorado. 73 pp.

  • Elliott, B. A., S. Spackman Panjabi, B. Kurzel, B. Neely, R. Rondeau, M. Ewing. 2009. Recommended Best Management Practices for Plants of Concern. Practices developed to reduce the impacts of oil and gas development activities to plants of concern. Unpublished report prepared by the Rare Plant Conservation Initiative for the National Fish and Wildlife Foundation.

  • 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.

  • O'Kane, S. L. 1988. Colorado's Rare Flora. Great Basin Naturalist. 48(4):434-484.

  • O'Kane, S.L. 1987. Status report for Physaria obcordata. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

  • O'Kane, S.L. 1987. Status report for Physaria obcordata. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

  • Roberts, R. 1990. White River RMP/EIS Management Situation Analysis, Resource Area Profile.

  • 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.

  • Rollins, R.C. 1983. Studies in the Cruciferae of western North America. J. Arnold Arboretum 64(4): 491-501.

  • Rollins, R.C. 1993a. The Cruciferae of continental North America: Systematics of the mustard family from the Arctic to Panama. Stanford Univ. Press, Stanford, California. 976 pp.

  • 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. 1990. Endangered and threatened wildlife and plants: final rule to determine Lesquerella congesta and Physaria obcordata to be threatened species.

  • U.S. Fish and Wildlife Service. 1993. Dudley Bluffs bladderpod and Dudley Bluffs twinpod recovery plan. Denver, 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.

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