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Montana Field Guide

Montana Field Guides

Long-styled Thistle - Cirsium longistylum

Species of Concern
Native Species

Global Rank: G2G3
State Rank: S2S3
(see State Rank Reason below)

Agency Status
MNPS Threat Rank: 1

External Links

State Rank Reason (see State Rank above)
Population estimates of approximately 30,000 plants, including seven high quality populations, scattered over four mountain ranges are promising for the long-term viability of the species. Habitat in the largest populations is generally of high quality with few if any problem weeds posing significant and immediate threats. In the near future, little change in habitat quality is expected in these populations. Sites are mostly on National Forest lands that provide a degree of protection and two large populations on private lands that have a history of light to moderate grazing appear stable. Also of benefit at this time is the active weed control program employed by the private landowners on their lands.

Long- and short-term population trends are difficult to gauge due to the lack of good survey data over many years. However, available data and observations provide some evidence that population levels have at least remained fairly stable over the past decade, with significant yearly fluctuations possible. Threats posed by invasive weeds and the introduced bio-control agent do provide reason for concern.
  • Details on Status Ranking and Review
    Long-styled Thistle (Cirsium longistylum) Conservation Status Review
    Review Date = 06/06/2012
    View State Conservation Rank Criteria
    Population Size

    Score1 - Moderate: Generally 10,000-100,000 individuals.

    Range Extent

    Score3 - Local Endemic or Very Small Montana Range: Generally restricted to an area <10,000 sq. miles (equivalent to the combined area of Phillips and Valley Counties) or <6 Sub-basins (4th code watersheds) Range-wide OR limited to one Sub-basin in Montana

    Area of Occupancy

    Score0 - High: Occurs in >25 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).


    Score1-2 - Minor to Moderate Declines:


    Score3 - Very High: >70% of the populations are being negatively impacted or are likely to be negatively impacted in the near future by one or more activities or agents that are expected to result in decreased populations and/or decreasing habitat quality and/or quantity.

    CommentIntroduced Rhinocyllus weevil, noxious weeds and weed control efforts are the primary threats.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 9 to 11 total points scored out of a possible 19.

General Description
Long-styled Thistle has simple or branched stems that are 50-60 cm tall and up to 15 mm thick at the base; plants are perennial, producing daughter rosettes that live for two more years. The basal leaves are shallowly lobed, moderately spiny, green and glabrous above, and densely white-hairy below; the lower leaves are narrowly lance-shaped, up to 15 cm long, and lobed to 1/3 or less the leaf width. The smaller upper leaves are more ovate in outline with mostly entire margins and numerous marginal spines; the herbage is covered with long, tangled, white hairs. The inflorescence usually consists of a terminal cluster of 2 to several flower heads and a number of side branches which reach up to 15 cm long and have fewer heads; each flower head is ca. 30 mm high, 25 mm wide, and subtended by a few reduced leaves. The involucral bracts occur in two main series: the outer are narrowly lance-shaped with a yellowish, dilated, and fringed apex tipped by a slender spine; the inner bracts are more lance-shaped and longer. The white disk flowers are 20-22 mm long; ray flowers are absent. There are numerous tawny bristles which form a pappus at the tip of the achene.

Flowering in late June-August.

Diagnostic Characteristics
This species can best be distinguished from the closely-related C. hookerianum by the dilated and fringed involucral bracts.

Species Range

Range Comments
Endemic to central Montana with extant populations in Broadwater, Cascade, Judith Basin, Lewis & Clark, Meagher and Wheatland counties.

Observations in Montana Natural Heritage Program Database
Number of Observations: 205

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

C. longistylum occurs in a variety of open habitats that receive full to partial sun. The best habitats for the species occur in montane to subalpine meadows. Occurrences are also common along roadsides, herbaceous-dominated riparian areas and open forests of Douglas-fir, lodgepole pine or whitebark pine. Plants occur as low 4800 feet elevation up to approximately 8100 feet with the majority of the occurrences between approximately 6000 and 7500 feet. Known occurrences of C longistylum are predominantly on calcareous soils derived from dolomites, limestones or shales.

Ecological Systems Associated with this Species

  • Additional ReferencesLegend:   View Online Publication
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    • Achuff, P. L. and L. A. Schassberger Roe. 1991. Weeds and rare native plants in Montana. Proc. Weed Symposium (1991): 18-23.
    • Biosystems Analysis, Inc. 1994. Endangered species biological survey final report. [Contract F24604 93 C0324]. Submitted to D. Spitzer, Malmstrom Air Force Base. 47 pp. plus appendices.
    • Brunsfeld, S.J. and C.T. Baldwin. 1994. Preliminary genetic analysis of Cirsium longistylum (Long-styled thistle), a candidate threatened species. Unpublished report prepared for the U.S. Fish and Wildlife Service, Region 4. Wildland Plant Ecogenetics Cooperative, in cooperation with the Montana Natural Heritage Program, Helena. 20 pp. plus appendices.
    • Heidel, B. L. 1992. Field survey to Carl Creek - Helena National Forest of 14 July.
    • Heidel, B.L. 1994. Monitoring study of Cirsium longistylum (long-styled thistle), a candidate threatened species. Unpublished report prepared for U.S. Fish and Wildlife Service, Region 4. Montana Natural Heritage Program, Helena, MT. 32 pp.
    • Kratz, A. 1987. Field work in Paine Gulch with Wayne Phillips (USFS): 29 June - 2 July.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Mathews, S.Y. 1990. Cirsium longistylum project: summary report. Unpublished report. Montana Natural Heritage Program, Helena, MT. 3 pp.
    • Mincemoyer, S. 2004. Range-wide status assessment of Cirsium longistylum (long-styled thistle). Report to Burnett Land, LLC. Montana Natural Heritage Program, Helena, MT. 22 pp. + appendices.
    • Moore, R.J. and C. Frankton. 1963. Cytotaxonomic notes on some Cirsium species of the western United States. Canadian Journal of Botany 41:1553-1567.
    • Poole, J. M. 1992. [Field survey to Little Belt Mountains, Lewis and Clark National Forest of July 20-24, 1992.]
    • Poole, J. M. 1992. [MTNHP Field Survey of Elkhorn and Big Belt Mountains, Helena National Forest, of July 12, 27-29, August 3-7, 14, 17, 26 and 27.]
    • Poole, J. M. 1992. [MTNHP Field Survey, Little Belt and Castle Mountains, Lewis and Clark National Forest, August 18-20.]
    • Poole, J.M. and B.L. Heidel. 1993. A taxonomic assessment and monitoring study of the Long-styled Thistle (Cirsium longistylum). Unpublished report to the U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena, MT. 97 pp.
    • Poole, J.M. and B.L. Heidel. 1993. Sensitive plant surveys in the Big Belt and Elkhorn Mountains, Helena National Forest, Montana. Unpublished report to the Helena National Forest. Montana Natural Heritage Program. Helena, MT. 129 pp. plus printouts, maps.
    • Ramstetter, J. 1983. Site survey and special plant survey form(s).
    • Ramstetter, Jennifer. Department of Botany, University of Massachusetts, Amherst, MA 01003. 413/545-2238. Personal communication to the Montana Natural Heritage Program.
    • Schassberger, L.A. 1990. Field surveys and monitoring of 23-27 and 30-31 July and 6-10 August in the Little Belt Mountains (Cirsium longistylum, Goodyera repens).
    • Schassberger, L.A. 1991. Report on the conservation status of Cirsium longistylum, a candidate threatened species. Unpublished report. Montana Natural Heritage Program, Helena, MT 92 pp.
    • Schassberger, L.A. and P.L. Achuff. 1991. Status review of Cirsium longistylum, Lewis and Clark National Forest. Montana Natural Heritage Program. Helena, MT 78 pp.
    • Shelly, J.S. 1986. [Field Surveys in Lewis & Clark, Pondera, and Meagher Cos. Of 22-24 July.]
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Citation for data on this website:
Long-styled Thistle — Cirsium longistylum.  Montana Field Guide.  .  Retrieved on , from