Roadless Areas
Home/Species/ Long-styled Thistle

Cirsium longistylum

Moore & Frankton

Long-styled Thistle

G3Vulnerable Found in 1 roadless area NatureServe Explorer →
G3VulnerableGlobal Rank
MediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.131907
Element CodePDAST2E1P0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderAsterales
FamilyAsteraceae
GenusCirsium
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.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2024-12-16
Change Date2024-12-16
Edition Date2024-11-13
Edition AuthorsMincemoyer, S (2004), rev. Johnson, J. (2024)
Threat ImpactMedium
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Cirsium longistylum is a biennial herb that is endemic to central Montana in the western United States. Habitat in the largest populations is generally of high quality with few if any problem weeds posing significant and immediate threats. 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. Threats posed by invasive weeds and the introduced bio-control agent do provide a reason for concern but active weed control programs benefit this species.
Range Extent Comments
Cirsium longistylum is endemic to central Montana, United States, with extant populations in Broadwater, Cascade, Judith Basin, Lewis & Clark, Meagher, and Wheatland counties. One historic occurrence in Fergus County has not been observed since 1960. Range extent was estimated using herbarium specimens and NatureServe Network occurrence data collected between 1993 and 2024 (CPNWH 2024, NatureServe 2024, SEINet 2024).
Occurrences Comments
Based on herbarium records and NatureServe Network occurrence data documented between 1993 and 2024, there are 92 occurrences rangewide (CPNWH 2024, NatureServe 2024, SEINet 2024).
Threat Impact Comments
The most significant threats to Cirsium longistylum are from the spread of the non-native plants Canada Thistle (Cirsium arvense), Common Hound’s-tongue (Cynoglossum officinale), and Spotted Knapweed (Centaurea stoebe) and from the introduced inflorescence-feeding weevil Rhinocyllus conicus, introduced to control Musk thistle (Carduus nutans) (Montana Natural Heritage Program [2021 data, accessed 2024]). Herbicides for these invasive species may be inadvertently applied to Cirsium longistylum.
Ecology & Habitat

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.

Diagnostic Characteristics

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

Habitat

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 (Montana Natural Heritage Program 2024).
Terrestrial Habitats
Forest/WoodlandForest EdgeWoodland - ConiferGrassland/herbaceous
Other Nations (1)
United StatesN3
ProvinceRankNative
MontanaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
8 - Invasive & other problematic species, genes & diseasesLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
8.1.2 - Named speciesLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
9 - PollutionRestricted (11-30%)Serious - moderateHigh (continuing)
9.3 - Agricultural & forestry effluentsRestricted (11-30%)Serious - moderateHigh (continuing)
9.3.3 - Herbicides and pesticidesRestricted (11-30%)Serious - moderateHigh (continuing)

—

Plant Characteristics
DurationBIENNIAL, Short-lived
Economic Value (Genus)No
Roadless Areas (1)
Montana (1)
AreaForestAcres
Middle Fork Judith WsaLewis and Clark National Forest81,131
References (17)
  1. Achuff, P.L., and L.A. Schassberger Roe. 1992. Weeds and rare native plants in Montana. Proceedings Weed Symposium (1991): 18-23.
  2. 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.
  3. 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.
  4. Consortium of Pacific Northwest Herbaria (CPNWH). 2024. Online database of vascular plant specimens from the Pacific Northwest. Online. Available: http://www.pnwherbaria.org/index.php (accessed 2024).
  5. Dorn, R.D. 1984. Vascular plants of Montana. Mountain West Publishing, Cheyenne, Wyoming. 276 pp.
  6. 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.
  7. 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.
  8. Mathews, S.Y. 1990. CIRSIUM LONGISTYLUM project: summary report. Unpublished report. Montana Natural Heritage Program, Helena, MT. 3 pp.
  9. Montana Natural Heritage Program. 2024. Montana Field Guide. Online. Available: http://fieldguide.mt.gov (Accessed 2024).
  10. Moore, R. J. and C. Frankton. 1963. Cytotaxonomic notes on some <i>Cirsium </i>species of the western United States. Canadian Journal of Botany 41:1553-1567.
  11. NatureServe. 2024. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  12. Poole, J. M. and B. L. Heidel. 1993a. 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.
  13. Poole, J. M. and B. L. Heidel. 1993b. 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.
  14. Ramstetter, Jennifer. Department of Botany, University of Massachusetts, Amherst, MA. Personal communication to the Montana Natural Heritage Program.
  15. 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.
  16. 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.
  17. Southwest Environmental Information Network (SEINet). 2024. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2024).