Scientific Name : Mentzelia speciosa
Author : Osterhout
NatureServe Explorer
Common Name : Jeweled Blazingstar
Current Research Activities
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Taxonomy
Loasaceae (blazingstar family)
The taxon formerly treated as two species (M. sinuata and M. speciosa) is treated as M. speciosa (Ackerfield 2015, 2022). Weber and Wittmann (2012) lump Nuttallia chrysantha, N. densa, N. reverchonii, N. sinuata, and N. speciosa all under Nuttallia multiflora, noting that further study is needed.
Ranks and Status
State Rank : S3S4
State Rank Reason : Mentzelia speciosa is known from over 100 occurrences, many of which are poorly documented or historical; this wide ranging species is threatened by residential development, road maintenance, motorized and non motorized recreation and encroachment by non-native species.
U.S. Endangered Species Act : none
Colorado Threatened and Endangered List : none
Other Statuses : none
Description and Phenology
General Description:
Herbaceous perennial or biennial, 3-5 dm tall, with bright yellow flowers. Stems are white, slender to stout, and branched. Leaves usually do not have a broad and clasping base. The outer fertile stamens have broad filaments, grading to inner stamens with narrow filaments. Seeds are smooth in appearance at 10X (Ackerfield 2012). Characteristic of the Blazingstar Plant Family, the leaves are covered with hairs that adhere to clothing or fur like velcro.
Look Alikes:
Mentzelia nuda plants are taller and more stout, and have white to light yellow flowers. Mentzelia speciosa flowers are bright yellow.
Phenology:
Flowers May through early September, and fruit in August and September (Colorado Natural Heritage Program 2012) .
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Habitat
The habitat for this species has not been clearly defined. Many of the occurrences are found in sandy soils derived from granitic parent materials within pinyon-juniper woodlands. Plants have also been documented in gravel and ash soils, and in association with Ponderosa pine, Douglas fir, and Gambel's oak (Colorado Natural Heritage Program 2012).
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Elevation Range:
5,242 - 10,852 feet (1,598 - 3,308 meters)
Distribution
Colorado Endemic:
No
Range:
Mentzelia speciosa is known in Colorado, USA, from the following 19 counties: Alamosa, Arapahoe, Boulder, Chaffee, Clear Creek, Custer, Denver, Douglas, El Paso, Fremont, Gilpin, Jefferson, Larimer, Las Animas, Mineral, Park, Pueblo, Saguache, Teller. Estimated range extent in Colorado of 64,337 square kilometers was calculated in GeoCAT using occurrence data provided by the Colorado Natural Heritage Program (2025) and additional specimen label data from SEINet (2025). This species is also found in Wyoming and New Mexico.
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Threats and Management Issues
The primary threats are from residential development, road maintenance, and recreation activities. Many occurrences are found in disturbed areas such as road cuts (Colorado Natural Heritage Program 2012).
References
- Ackerfield, J. 2015. Flora of Colorado. BRIT Press, Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.
- Ackerfield, J. 2022. Flora of Colorado. Second Edition. Bot. Misc. 60. BRIT Press, Fort Worth Botanic Garden/Botanical Research Institute of Texas, U.S.A. 861 pp.
- Colorado Natural Heritage Program (CNHP). 2025. Biodiversity Tracking and Conservation System (Biotics 5). Colorado Natural Heritage Program, Colorado State University, Fort Collins.
- Colorado Natural Heritage Program. 2012. Biodiversity Tracking and Conservation System. Colorado State University, Fort Collins, CO.
- Harrington, H.D. 1954. Manual of the plants of Colorado. Sage Press, Chicago. 666 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).
- SEINet. 2025. Southwest Environmental Information Network; Regional Herbaria Network Collections Database. http://swbiodiversity.org/seinet/collections/index.php?catid=2.
- USDA, NRCS. 2022. 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.
