Penstemon degeneri - Crosswhite
Degener's Beardtongue
Other Common Names: Degener's beardtongue
Taxonomic Status: Accepted
Related ITIS Name(s): Penstemon degeneri Crosswhite (TSN 33875)
Unique Identifier: ELEMENT_GLOBAL.2.133684
Element Code: PDSCR1L1X0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Figwort Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Scrophulariales Scrophulariaceae Penstemon
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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: Penstemon degeneri
Conservation Status
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NatureServe Status

Global Status: G2
Global Status Last Reviewed: 08May2015
Global Status Last Changed: 23Oct1995
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G2 - Imperiled
Reasons: A narrow endemic, known from 13 occurrences in and around the Arkansas River Canyon in Colorado.  This Penstemon species faces several threats including recreation in US Forst Service lands, grazing, trampling, herbivory, and non-native plants.
Nation: United States
National Status: N2

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 (S2)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: A Colorado endemic, this species is known from Fremont, Custer, and Chaffee counties. Estimated range is 2,445 square kilometers (944 square miles), calculated in GIS by drawing a minimum convex polygon around the known occurrences (calculated by the Colorado Natural Heritage Program in 2008).

Area of Occupancy: 1-25 4-km2 grid cells
Area of Occupancy Comments: The total occupied habitat is about 575 acres. Occurrences without specific information on occupied habitat were considered to occupy 0.5 acre.

Number of Occurrences: 6 - 20
Number of Occurrences Comments: There are 13 principal occurrences documented in the Colorado Natural Heritage Program database. One of the 13 occurrences has not been observed in over 20 years. Beatty (2004) reports that this species is known from 14 sites. It is likely that this discrepancy in the total number of occurrences is because one of the sites reported by Beatty is represented in the Heritage database as a portion of another occurrence and is not reported separately.

Population Size Comments: Total estimated sum of individuals from 6 of the 13 occurrences is 1,518. The remaining occurrences do not report the number of individuals.

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

Overall Threat Impact: High
Overall Threat Impact Comments: Motorized recreation is considered to be the primary threat to the species at this time (Rondeau et al. 2011). Penstemon degeneri is vulnerable because of its restricted geographic range, the small number of documented occurrences, and its vulnerability to human-related and environmental threats. Disturbances and land management activities may maintain suitable habitat for this species or negatively impact existing populations, depending on the disturbance intensity, frequency, and type. Threats to the long-term persistence of P. degeneri populations or habitats likely differ for each of the occurrences. The most significant threats to the occurrences on National Forest System lands include motorized and non-motorized recreation, non-native plant invasion, grazing and trampling, extensive herbivory, succession, and global environmental changes. Populations near roads, trails, or campgrounds are at higher risk for the detrimental effects of road or trail associated activities and non-native plant invasion (Beatty et al. 2004).

Short-term Trend: Unknown
Short-term Trend Comments: No population trend data exists (Beatty et al. 2004).

Long-term Trend: Unknown
Long-term Trend Comments: No population trend data exists (Beatty et al. 2004).

Other NatureServe Conservation Status Information

Distribution
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Global Range: A Colorado endemic, this species is known from Fremont, Custer, and Chaffee counties. Estimated range is 2,445 square kilometers (944 square miles), calculated in GIS by drawing a minimum convex polygon around the known occurrences (calculated by the Colorado Natural Heritage Program in 2008).

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
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U.S. Distribution by County Help
State County Name (FIPS Code)
CO Custer (08027), Fremont (08043), Park (08093), Teller (08119)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
11 Arkansas Headwaters (11020001)+, Upper Arkansas (11020002)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A slender perennial herb, 2-4 dm tall, with 2-10 tubular, blue flowers on the top portion of the stems.
General Description: Penstemon degeneri is a perennial herb from 25 to 40 cm tall with five or more, slender (1.0 to 2.5 mm diameter at base), leafy, short-pubescent stems and a suffrutescent caudex. The basal leaves are lanceolate, entire, and up to 6 cm long and 16 mm wide (Spackman et al. 1997). The cauline leaves are more linear, more pubescent, and more sessile. The unleafy, sparingly glandular inflorescence is 3 to 10 cm high, with 2 to 10 tubular flowers at the ends of the stems. The dark blue to violet corolla of the flower is gradually inflated, 14 to 19 mm long and 4 to 5 mm wide at the mouth. The corollas are slightly two-ridged on the floor and have straight, reddish guidelines and sparse yellow hairs in the corolla throat. The staminode is also bearded with sparse golden hairs for about half its length. The anther sacs are 2.0 mm across the connective and are longer than wide. The papery calyx is persistent and the dehisced capsules are 7 to 9 mm long, with small, dark brown, irregularly angled seeds (Beatty et al. 2004).
Diagnostic Characteristics: From Beatty et al. 2004: The characteristics used to distinguish Penstemon degeneri from other penstemons include leaf morphology, the size of the anther sacs, the color and density of hairs in the corolla throat, growth form, and geography. Penstemon degeneri can be easily confused with other Penstemon species that may overlap in distribution (i.e., P. gracilis, P. virens). Penstemon gracilis, of Colorado's eastern slope, has finely toothed leaves, a pale blue corolla, and whitish corolla hairs. Penstemon virens has a corolla 10 to 25 mm long and totally glabrous stems; it tends to grow in patches or mats with numerous stems, whereas P. degeneri tends to grow more singly and has minutely pubescent stems (Weber and Wittmann 2001). Penstemon degeneri generally lacks a basal rosette when in flower, but there can be conspicuous basal or low cauline leaves that make this characteristic confusing. Penstemon radicosus is found in north-central Colorado. The strongly two-ridged corolla floor and staminode of P. inflatus (New Mexico) have such dense yellow hairs that the corolla throat is sometimes closed. Penstemon griffinii is found to the west of Fremont County, from Park County to Mineral and Conejos counties. Contrary to P. degeneri, P. griffinii retains a basal rosette throughout its flowering period, has smaller stem leaves (2 to 3 cm long and 2 cm wide), a slightly larger corolla, and dense golden hairs in its throat (Spackman et al. 1997, Weber and Wittmann 2001). Several observers noted other individual variations in P. degeneri, including smaller stature, few-flowered, whitish hairs in the flower throat, and lavender or magenta flowers (Colorado Natural Heritage Program element occurrence records 2003). Whenever possible, it is best to obtain a specimen of P. degeneri for identification verification (Spackman personal communication 2003). Technical descriptions of this species are presented in Crosswhite (1965a) and Peterson and Harmon (1981). Keys to Penstemon in Colorado are available in Weber and Wittmann (2001) and Jennings (1998). Photos and illustrations are available in Spackman et al. (1997).
Terrestrial Habitat(s): Bare rock/talus/scree, Forest Edge, Forest/Woodland, Grassland/herbaceous, Woodland - Conifer
Habitat Comments: This species is found in open pinyon-juniper woodlands and montane grasslands, in rocky soils with igneous bedrock.  The plants grow mainly near the rim of canyons, and also in cracks of large rock slabs, in full sun or shade.  Associated species include Quercus gambelii, Sitanion longifolium, Verbena bacteata, Lesquerella montana, Grindelia squarrosa, Heterotheca horrida, Artemisia frigida, Carex stenophylla, Eriogonum jamesii, Opuntia phaeacantha, Atriplex canescens, Pinus edulis, and Juniperus monosperma (Peterson and Harmon 1981).
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: 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: 27Sep2000
Author: Spackman, S., and D. Anderson.
Population/Occurrence Viability
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Excellent Viability: Size: 1000 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 species may require periodic fire to open the canopy of its pinyon- juniper woodland habitat. 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 to be relatively resilient.
Good Viability: Size: 100 or more 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: 15 to 100 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 significant human disturbance, but the ecological processes needed to sustain the species are still intact.
Poor Viability: Size: Less than 15 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. 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
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 23May2006
NatureServe Conservation Status Factors Author: Spackman, Susan, rev. Maybury/Spackman (1996), rev. Spackman, S. and D. Anderson (2000), rev. Neuhaus, K., J. Handwerk, and S. Spackman Panjabi (2006), rev. Oliver, L. (2015)
Element Ecology & Life History Edition Date: 05Mar2007
Element Ecology & Life History Author(s): Susan Spackman Panjabi, rev. SSP (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
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  • Ackerfield, J. 2012. The Flora of Colorado. Colorado State University Herbarium. 433 pp.


  • Beatty, B.L., W.F. Jennings, and R.C. Rawlinson (2004, February 23). Penstemon degeneri Crosswhite (Degeners beardtongue): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/penstemondegeneri.pdf.

  • Beatty, B.L., W.F. Jennings, and R.C. Rawlinson. (2004, February 23). Penstemon degeneri Crosswhite (Degeners beardtongue): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/penstemondegeneri.pdf.

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

  • Crosswhite, F.S. 1965. Revision of Penstemon section Penstemon (Scrophulariaceae) II. A western alliance in series Graciles. American Midland Naturalist 74:429.

  • 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.

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

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

  • 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. 

  • Spackman, S., B. Jennings, J. Coles, C. Dawson, M. Minton, A. Kratz, and C. Spurrier. 1997. Colorado Rare Plant Field Guide. Prepared for the Bureau of Land Management, the U.S. Forest Service and the U.S. Fish and Wildlife Service by the Colorado Natural Heritage Program.

  • 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.

  • 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.

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