Physaria bellii - Mulligan
Bell's Twinpod
Taxonomic Status: Accepted
Related ITIS Name(s): Physaria bellii Mulligan (TSN 23273)
Unique Identifier: ELEMENT_GLOBAL.2.135965
Element Code: PDBRA22030
Informal Taxonomy: Plants, Vascular - Flowering Plants - Mustard Family
Image 21744

© Loraine Yeatts

 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Capparales Brassicaceae Physaria
Check this box to expand all report sections:
Concept Reference
Help
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 bellii
Conservation Status
Help

NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 22Sep2011
Global Status Last Changed: 19May2008
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G2 - Imperiled
Reasons: Restricted to outcrops of the Niobrara and Pierre formations, and red sandstone outcrops (Fountain, Ingleside, and Lykins formations) in northcentral Colorado. There are 25 occurrences with as many as one million individual plants. However, the species faces variety of threats including mining, suburban expansion along the Front Range, road construction, and invasion of its habitat by noxious weeds such as diffuse knapweed (Centaurea diffusa).
Nation: United States
National Status: N2N3

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 (S2S3)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Endemic to Colorado; known from Boulder and Larimer counties. Restricted to Niobrara and Pierre Shale Formations.

Area of Occupancy: 6-25 4-km2 grid cells
Area of Occupancy Comments: The total occupied habitat is about 1,675 acres. Occurrences without specific information on occupied habitat were considered to occupy 0.5 acre.

Number of Occurrences: 21 - 80
Number of Occurrences Comments: There are 25 principal occurrences documented in the Colorado Natural Heritage Program database. Three of the 25 occurrences have not been observed in over 20 years (as of 2011).

Population Size Comments: Total estimated sum of individuals from 23 of the 25 documented occurrences is 131,526. The remaining occurrences do not report the number of individuals. There have been 10,000+ individuals documented in a total ground area of 10,000 meters squared on City of Boulder Open Space, and estimates that 1 million Physaria bellii plants exist on City of Boulder Open Space land (pers. comm. Carpenter 1996).

Number of Occurrences with Good Viability/Integrity: Few (4-12)
Viability/Integrity Comments: There are 11 occurrences with an A or B rank.

Overall Threat Impact: High
Overall Threat Impact Comments: The primary threat is from residential development along the Front Range of Colorado. Additional potential threats are limestone mining operations, and road construction and maintenance. Invasion of habitat by noxious weeds such as cheatgrass, smooth brome, and diffuse knapweed, may also be a threat to some occurrences. Many occurrences have been destroyed or degraded by limestone mining and housing subdivisions, however, the largest and highest quality occurrences are still viable.

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Probably declining because of suburban expansion and mining.

Long-term Trend: Unknown
Long-term Trend Comments: Unknown.

Intrinsic Vulnerability Comments: Assessment of vigor unknown (Peterson et al. 1981), though plants seem healthy and robust at most occurrences and have been observed growing on road-cuts and mine tailings (CNHP 1997).

Other NatureServe Conservation Status Information

Distribution
Help
Global Range: Endemic to Colorado; known from Boulder and Larimer counties. Restricted to Niobrara and Pierre Shale Formations.

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 Boulder (08013), Larimer (08069)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
10 St. Vrain (10190005)+, Big Thompson (10190006)+, Cache La Poudre (10190007)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Help
Basic Description: A perennial herb with semi-prostrate flowering stems, 5-12.5 cm long, radiating from a basal rosette of silvery-green leaves so that the rosette is often encircled with yellow flowers during the May-June flowering period.
General Description: Perennials with dense racemes of yellow flowers and basal leaves that form a strong rosette.  Plants rise from a simple caudex that is densely (silvery) pubescent.  The stems are simple from the base of the plants, decumbent to nearly prostrate, and 0.5-1.3 dm long. Basal leaf blades are broadly obovate, with shallowly dentate margins. Cauline leaves are oblanceolate to broadly obovate, 1-2.5 cm, with entire margins. Fruits are arranged in pairs (hence the common name twinpod).  The fruit pods are slightly flattened (contrary to replum) to uncompressed, 4-9 × 2-8 mm, and the apical and basal sinuses are narrow and deep.
Technical Description: From the Flora of North America (2010): Perennials; caudex simple, (relatively large); densely (silvery) pubescent, trichomes (sessile, appressed), rays furcate, fused at base. Stems simple from base, decumbent to nearly prostrate, 0.5-1.3 dm. Basal leaves (strongly rosulate; shortly petiolate); blade broadly obovate, 1.5-7.5 (width 7.5-26 mm, base gradually tapering to petiole), margins shallowly dentate, (apex obtuse). Cauline leaves: blade oblanceolate to broadly obovate, 1-2.5 cm, margins entire. Racemes dense. Fruiting pedicels (divaricate-ascending to widely spreading, slightly sigmoid to curved), 7-12 mm. Flowers: sepals (pale yellow or yellow-green), narrowly lanceolate to narrowly deltate, 4-8 mm; petals yellow, broadly spatulate to obovate, 9-13 mm, (not clawed). Fruits didymous, slightly flattened (contrary to replum) to uncompressed, 4-9 × 2-8 mm, (strongly coriaceous, apical and basal sinuses narrow, deep); valves (retaining seeds after dehiscence), pubescent, trichomes appressed; replum narrowly oblanceolate to narrowly linear-oblong, as wide as or wider than fruit, apex obtuse; ovules 4 per ovary; style more than 3 mm. Seeds compressed. 2n = 8.
Terrestrial Habitat(s): Bare rock/talus/scree, Grassland/herbaceous
Habitat Comments: Physaria bellii is found along the Front Range foothills often in shale and limestone soils of the Fountain/Ingleside, Lykins, Niobrara, and Pierre formations. This species is found in association with grassland and shrubland habitats, in rocky areas and road cuts.  Commonly associated taxa include: Cercocarpus montanus, Oryzopsis hymenoides, Guiterrezia sarothrae, Rhus trilobata, Lesquerella ludoviciana, Heterostipa neomexicana. Penstemon secundiflorus, Eriogonum brevicaule, Opuntia, Dalea,Yucca, Sphaeralcea, and Heterotheca (Flora of North America 2010, Colorado Natural Heritage Program 2013).
Economic Attributes Not yet assessed
Help
Management Summary Not yet assessed
Help
Population/Occurrence Delineation
Help
Minimum Criteria for an Occurrence: Any naturally occurring population that is separated by a sufficient distance or barrier from a neighboring population. As a guideline, EOs are separated by either: 1 mile or more across unsuitable habitat or altered and unsuitable areas; or 2 miles or more across apparently suitable habitat not known to be occupied. 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 populations will eventually be found to be more closely connected; these are best regarded as suboccurrences. No information on mobility of pollen and propagules is available on which to base the separation distance for this species.
Date: 28Sep2000
Author: Spackman, S., and D. Anderson.
Population/Occurrence Viability
Help
Excellent Viability: Size: A robust population of 50,000 or more individuals on 50 or more acres (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. Physaria bellii is tolerant of anthropogenic disturbance to some extent and may colonize areas such as mine talings, but an A- ranked occurrence must be a population on a naturally disturbed substrate. Justification: Large populations in high quality sites are presumed to contain a high degree of genetic variability, to have a low susceptibility to the effects of inbreeding depression, and tobe relatively resilient.
Good Viability: Size: 1,000 or more individuals on 10 or more acres (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: 100 or more individuals occupying 5 or more acres (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 significant human disturbance, but the ecological processes needed to sustain the species are still intact.
Poor Viability: Size: Less than 100 individuals on up to 5 acres (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. The occurrence has a low probability of long-term persistence due to inbreeding depression, natural stochastic events, and its intrinsic vulnerability to human impacts.
Justification: Justification: EOs not meeting "C"-rank criteria are likely to have a very high probability of inbreeding depression and extirpation due to natural stochastic processes and/or occur in degraded habitat with low long-term potential for survival.
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
Help
Authors/Contributors
Help
NatureServe Conservation Status Factors Edition Date: 22Sep2011
NatureServe Conservation Status Factors Author: DT Wasinger, rev. Spackman/Maybury (10/96), rev. Spackman, S. and D. Anderson (2000), rev. Neuhaus, K., J. Handwerk, and S.S. Panjabi (2006), rev. Handwerk, J. (2011)
Element Ecology & Life History Author(s): rev. SSP (2013)

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.


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

  • Jennings, W. 1989. Final Report Colorado Natural History Small Grants Program. Prepared for The Nature Conservancy.

  • 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.

  • Mulligan, G.A. 1966. Two new species of Physaria in Colorado. Canadian Journal of Botany, vol. 44, pp. 1661-1665.

  • 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.

  • Peterson, J. S. and W. Harmon. 1981. Status report for Physaria bellii. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

  • Peterson, J. S. and W. Harmon. 1981. Status report for Physaria bellii. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

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

  • 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.

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2018.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2018 NatureServe, 4600 N. Fairfax Dr., 7th Floor, Arlington Virginia 22203, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.