Mentzelia densa - Greene
Royal Gorge Stickleaf
Other English Common Names: Royal Gorge Blazingstar
Other Common Names: Royal Gorge blazingstar
Synonym(s): Nuttallia densa (Greene) Greene
Taxonomic Status: Accepted
Related ITIS Name(s): Mentzelia densa Greene (TSN 503767)
Unique Identifier: ELEMENT_GLOBAL.2.151385
Element Code: PDLOA030D0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Blazingstar Family
Image 12105

Public Domain

 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Violales Loasaceae Mentzelia
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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: Mentzelia densa
Taxonomic Comments: Weber and Wittmann (2012) lumped M. densa within Nuttallia speciosa. However, the University of Colorado Herbarium does have 21 specimens identified as Nuttallia densa (=Mentzelia densa); most are from Fremont County, with one from Chaffee County.
Conservation Status
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NatureServe Status

Global Status: G2
Global Status Last Reviewed: 09Jun2015
Global Status Last Changed: 23Oct1995
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G2 - Imperiled
Reasons: There are 16 occurrences known, and about 6 are of good viability. This is a locally common, narrow endemic of the drainages and main canyon of the Arkansas River in central Colorado (a range only about 40 km long). Threats to the species include recreational use of habitat, highway construction and maintenance and, residential/vacation home development.
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: Endemic to Colorado; known from Fremont County, and adjacent Chaffee County.  Estimated range is 2,545 square kilometers (982 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: 26-125 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 6 - 20
Number of Occurrences Comments: There are 16 principal occurrences documented in the Colorado Natural Heritage Program database. Three of the 15 occurrences have not been observed in over 20 years.

Population Size Comments: Total estimated sum of individuals from 10 of the 15 occurrences is 13,569. 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 6 occurrences with an A or B rank.

Overall Threat Impact: High
Overall Threat Impact Comments: Recreational use is considered to be the primary threat to the species at this time (Rondeau et al. 2011). Plants are restricted to the Arkansas River Valley and threats in the area are high (general area is being developed at a rapid rate, recreational development including ORV use, and highway construction and maintenance). Recreational use of the area is expected to increase. Plants are restricted to specific habitats within a small area.

Short-term Trend: Unknown

Long-term Trend: Unknown
Long-term Trend Comments: 2 Historic EOs.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Endemic to Colorado; known from Fremont County, and adjacent Chaffee County.  Estimated range is 2,545 square kilometers (982 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
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CO Chaffee (08015), Fremont (08043)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
11 Arkansas Headwaters (11020001)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A biennial herb that forms a hemispherical ball, up to 3 dm high, and produces yellow-petaled, flowers in mid-summer. Flowers open in late afternoon.
General Description: Mentzelia densa is a small perennial subshrub, usually less than 3 dm. tall. The stems branch from the base, giving the plant a hemispherical shape. The branches are white, curve upward and are covered with stiff hairs. The narrow leaves are also covered with stiff hairs. Bright yellow flowers occur singly or in threes at the ends of the branches, and open in the late afternoon. Flowers are about 2 cm. wide. The petals are narrow, widest at the middle, and pointed at the end. The fruit is oblong, 1.3 to 2 cm. long, 1 cm. in diameter and bears teeth that are about half as long as the fruit. Seeds are flattened and are surrounded by a thin, winglike membrane (Coles 1990).
Diagnostic Characteristics: Distinguished from other Mentzelia species by its tumbleweed growth form and the presence of the previous years dried stems (Spackman et al. 1997). The species is also recognized by its bright yellow flowers opening in the late afternoon, and the sticky hairs which cover that plants and cling to hair and clothing (Coles 1990).
Duration: PERENNIAL
Terrestrial Habitat(s): Forest Edge, Forest/Woodland, Shrubland/chaparral, Woodland - Conifer
Habitat Comments: Mentzelia densa occupies dry open areas in washes, roadsides, naturally disturbed sites, and steep rocky slopes. Plants grow in gravel, scree, or on cliffs formed from Precambrian granodiorite and gneiss. The species occurs in pinyon-juniper woodland and lower montane shrubland communities with a poorly developed understory and an open canopy. It may dominate in very open, disturbed sites such as sandy washes. It occurs as scattered individuals generally occupying 5% or less of the total vegetative canopy. The associated species are Pinus edulis, Juniperus monosperma, Juniperus scopulorum, Symphoricarpos oreophilus, Cercocarpus montanus, Artemisia tridentata, Eriogonum jamesii, Oryzopsis humenoides, Oryzopsis micrantha, Mentzelia multiflora var. leucopetala, Bouteloua gracilis, Rhus trilobata, Heterotheca villosa, Cylindropuntia inbricata, and Opuntia phaeacantha (Coles 1990).
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: 500 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, though tolerant of disturbance, has very narrow edaphic requirements. Natural disturbance by soil and scree movement and possibly by periodic fire may be required by this species. 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: 10 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 10 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: 09Jun2015
NatureServe Conservation Status Factors Author: Susan Spackman, rev. Spackman/Maybury (1996), rev. Spackman, S. and D. Anderson (2000), rev. Neuhaus, K., J. Handwerk, and S. Spackman Panjabi (2006), rev. A. Treher (2015)
Element Ecology & Life History Edition Date: 28Feb2007
Element Ecology & Life History Author(s): Susan Spackman Panjabi

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.


  • Coles, J. 1990. Status report for Mentzalia densa. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

  • Coles, J. 1990. Status report for Mentzalia densa. Unpublished report prepared for the Colorado Natural Areas Program, Denver, CO.

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

  • 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. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • 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. 1988. Colorado's rare flora. Great Basin Naturalist 48(4): 434-484.

  • 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.

  • Weber, W.A., and R.C. Wittmann. 2012a. Colorado Flora, Eastern Slope, a field guide to the vascular plants, fourth edition. University of Colorado Press. Boulder, Colorado. 555 pp.

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