Scientific Name : Packera debilis
Author : (Nutt.) Weber & Love
NatureServe Explorer
Common Name : Rocky Mountain Ragwort
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Taxonomy
Asteraceae (sunflower family)
Listed in Ackerfield (2015, 2022) as Packera debilis. Ackerfield reports that Packera pauciflora does not occur in Colorado, and that the Colorado plants identified as such are likely P. debilis. The Flora of North America includes both P. debilis and P. pauciflora but considers only P. debilis a Colorado taxon. Previous Colorado occurrences of P. pauciflora are now included here.
Ranks and Status
State Rank : S2S3
State Rank Reason : Known from approximately 35 occurrences in six counties; uncommon in moist meadows, stream sides, and fens.
U.S. Endangered Species Act : none
Colorado Threatened and Endangered List : none
Other Statuses : none
Description and Phenology
General Description:
Perennials, 2050+ cm; ± fibrous-rooted (caudices weakly branched, relatively short). Stems 1 or 24, clustered, bases sparsely floccose-tomentose or glabrous, leaf axils tomentose. Basal leaves (and proximal cauline, turgid) petiolate; blades elliptic to ovate or subreniform, 2040+ × 1530+ mm, bases cuneate to subcordate, margins subentire or crenate to crenate-dentate. Cauline leaves gradually reduced (sessile; pinnately lobed, sinuses deep, rounded, ultimate margins entire or subentire). Heads 620 in open or compact, corymbiform arrays. Peduncles ebracteate (or bractlets short), glabrous or sparsely hairy. Calyculi inconspicuous. Phyllaries 13 or 21, green (tips cyanic), 68+ mm, glabrous. Ray florets 0. Disc florets 4565+; corolla tubes 34 mm, limbs 23 mm. Cypselae 12 mm, glabrous; pappi 4.55.5 mm. (Flora of North America 1993+)
Look Alikes:
Often misidentified as Packera pauciflora which does not occur in Colorado (Culver and Lemly 2013).
Phenology:
June-August
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Habitat
Uncommon in moist meadows, stream sides, fens, usually with alkalinity (Culver and Lemly 2013).
Elevation Range:
7,852 - 10,080 feet (2,393 - 3,072 meters)
Distribution
Colorado Endemic:
No
Range:
Packera debilis is known from Grand, Jackson, Lake, Larimer, Park, and Summit counties. Estimated range extent in Colorado of 9902 square kilometers was calculated in GeoCAT using occurrence data provided by the Colorado Natural Heritage Program (2023). This species can also be found in Idaho, Montana, and Wyoming.
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Threats and Management Issues
This species is threatened by peat mining, alterations to hydrology, and residential development. Heavy grazing, has been documented in some occurrences, however, the long term effects of cattle grazing are unknown. Cirsium arvensis has been documented in drier areas, as well as Carduus nutans. Small range and area of occupancy make the species vulnerable to stochastic events.
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). 2023. Biodiversity Tracking and Conservation System (Biotics 5). Colorado Natural Heritage Program, Colorado State University, Fort Collins.
- Cronquist, A., A.H. Holmgren, N.H. Holmgren, J.L. Reveal, and P.K. Holmgren. 1984. Intermountain Flora: Vascular Plants of the Intermountain West, U.S.A. Vol. 4, Subclass Asteridae (except Asteraceae). New York Botanical Garden, Bronx. 573 pp.
- Culver, D.R. and J.M. Lemly. 2013. Field Guide to Colorado's Wetland Plants; Identification, Ecology and Conservation. Colorado Natural Heritage Program, Colorado State University, Fort Collins, 694 pp.
- Flora of North America Editorial Committee, ed. (FNA). 1993+. Flora of North America North of Mexico. Oxford Univ. Press, New York, Oxford.
- 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.
- Montana Natural Heritage Program. 1999. Biological Conservation Database. http://nris.state.mt.us/mtnhp. (May 15 1999).
- 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.
