Centaurea triumfettii - All.
Squarrose Knapweed
Other English Common Names: Squarrose Star-thistle
Other Common Names: squarrose knapweed
Synonym(s): Centaurea virgata Lam. ;Centaurea virgata var. squarrosa (Willd.) Boiss.
Taxonomic Status: Accepted
Related ITIS Name(s): Centaurea triumfettii All. (TSN 501352) ;Centaurea virgata Lam. (TSN 36978)
Unique Identifier: ELEMENT_GLOBAL.2.145869
Element Code: PDAST1Y0V0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Aster Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Asterales Asteraceae Centaurea
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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: Centaurea triumfettii
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA

U.S. & Canada State/Province Status
United States California (SNA), Montana (SNA), Nevada (SNA), Oregon (SNA), Utah (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Other NatureServe Conservation Status Information

Distribution
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U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States CAexotic, MTexotic, NVexotic, ORexotic, UTexotic

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
NV White Pine (32033)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Spring-Steptoe Valleys (16060008)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History Not yet assessed
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Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: Medium/Insignificant
Rounded I-Rank: Unknown
I-Rank Reasons Summary: Centaurea triumfettii, has a relatively restricted range in the western U.S. but appears to be spreading or was previously overlooked due to its similarity to other Centaurea species. It is most abundant in California, Utah, and Oregon but has also been found in Nevada, Washington, Idaho, Montana, Wyoming, Colorado, Arizona, and Michigan. Centaurea triumfettii usually occurs in dry open rangeland and areas with disturbance. Centaurea triumfettii is very competitive and can displace native rangeland plants. Seeds are abundant and easily spread by animals and humans. Management is moderately difficult. More information is needed especially about its ecological impacts.
Subrank I - Ecological Impact: Medium/Insignificant
Subrank II - Current Distribution/Abundance: Medium/Low
Subrank III - Trend in Distribution/Abundance: Medium
Subrank IV - Management Difficulty: High/Low
I-Rank Review Date: 10Sep2004
Evaluator: Tomaino, A.
Native anywhere in the U.S?
Native Range: Native to northern Africa, western Asia, and Europe (GRIN 2001).

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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Established outside cultivation in the U.S. (Kartesz 1999).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: Occurs in dry open rangeland with shallow soils (Wilson and Randall 2003).

Subrank I - Ecological Impact: Medium/Insignificant

1. Impact on Ecosystem Processes and System-wide Parameters:Low significance/Insignificant
Comments: No mention of changes in abiotic ecosystem processes or system-wide parameters found in the literature; assumption is that any alterations are not significant.

2. Impact on Ecological Community Structure:Medium/Low significance
Comments: Centaurea triumfettii is a long-lived perennial that grows 1 to 3 feet tall (Roche and Burrill 1996). Centaurea triumfettii is very competitive and can displace native rangeland plants (British Columbia Ministry of Agriculture, Food and Fisheries 2002).

3. Impact on Ecological Community Composition:High/Low significance
Comments: Centaurea triumfettii is very competitive and can displace native rangeland plants (British Columbia Ministry of Agriculture, Food and Fisheries 2002).

4. Impact on Individual Native Plant or Animal Species:Low significance/Insignificant
Comments: No mention of impacts on particular native species found in the literature; assumption is that any impacts are not significant.

5. Conservation Significance of the Communities and Native Species Threatened:Medium/Low significance
Comments: In Utah, it occurs on big sagebrush-bunchgrass rangeland, salt desert shrub range, juniper-dominated rangeland, and crested wheatgrass rangeland (Roche and Burrill 1996). In Oregon, it has invaded juniper-Idaho fescue rangeland and big sagebrush-bunchgrass rangeland (Roche and Burrill 1996). In California, it occurs in degraded juniper-shrub savanna (Roche and Burrill 1996). At least some of these communities may be of conservation significance but apparently, it is not often threatening elements of conservation significance.

Subrank II. Current Distribution and Abundance: Medium/Low

6. Current Range Size in Nation:Medium/Low significance
Comments: In California, it is known from four counties in the north and grows on more than 20,000 hectares (77 sq. mi.) (Moser and Crisp, not dated). In Utah, it is known from five counties and grows on over 100,000 acres (156 sq. mi.) (Roche and Burrill 1996). In Oregon, it is known from six counties (Rice 2004). In Nevada, it is known from one county (Kartesz 1988). In Michigan, it is known from 1 county (Voss 1996). In addition to these five states where Kartesz (1999) reports Centaurea triumfettii, six other states apparently have been invaded by this species. Known from one county in Montana and one county in Wyoming (Rice 2004). Known from western Colorado (Colorado Weed Masnagement Association 2000). Reported from Washington state (British Columbia Ministry of Agriculture, Food and Fisheries 2002). Reported from southern Idaho (Roche and Burrill 1996). Reported from Arizona, north of the Grand Canyon (Moser and Crisp, not dated). Centaurea triumfettii is probably more widespread than reported because of its close resemblance to the widespread Centaurea diffusa (Graham and Johnson 2004).

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Medium/Low significance
Comments: In Utah, it is known from five counties and grows on over 100,000 acres (156 sq. mi.) (Roche and Burrill 1996). In Utah, it occurs on big sagebrush-bunchgrass rangeland, salt desert shrub range, juniper-dominated rangeland, and crested wheatgrass rangeland (Roche and Burrill 1996). In Oregon, it is known from six counties (Rice 2004). In Oregon, it has invaded juniper-Idaho fescue rangeland and big sagebrush-bunchgrass rangeland with cheatgrass (Roche and Burrill 1996). In Washington and Oregon, Centaurea triumfettii is considered a red alert species with high potential to spread (WNPS 1997). Neither Centaurea triumfettii or its synonyms are listed as an exotic pest of greatest ecological concern by the California EPPC (CALEPPC 1999). Apparently, most negative impacts are in areas of Oregon and Utah.

8. Proportion of Nation's Biogeographic Units Invaded:Low significance
Comments: Approximately 15% of units, inferred from TNC (2001), Kartesz (1999), Rice (2004), Baldwin et al. (2004), Voss (1996), Kartesz (1988), Welsh (2003), Roche and Burrill (1996).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Low significance
Comments: Occurs in dry open rangeland with shallow soils (Wilson and Randall 2003). In California, it occurs in disturbed places (Baldwin et al. 2004) and degraded juniper-shrub savanna (Roche and Burrill 1996). In Utah, it occurs on roadsides and other disturbed sites (Welsh 2003), big sagebrush-bunchgrass rangeland, salt desert shrub range, juniper-dominated rangeland, and crested wheatgrass rangeland (Roche and Burrill 1996). In Oregon, it has invaded juniper-Idaho fescue rangeland and big sagebrush-bunchgrass rangeland with cheatgrass (Roche and Burrill 1996). In Nevada, it occurs on roadsides, grain fields, and waste places (Kartesz 1988). Areas most susceptible to invasion in Nevada are sagebrush and pinion-juniper rangelands (Graham and Johnson 2004).

Subrank III. Trend in Distribution and Abundance: Medium

10. Current Trend in Total Range within Nation:Moderate significance
Comments: In addition to these five states where Kartesz (1999) reports Centaurea triumfettii, six other states apparently have been invaded by this species. Known from one county in Montana and one county in Wyoming (Rice 2004). Known from western Colorado (Colorado Weed Masnagement Association 2000). Reported from Washington state (British Columbia Ministry of Agriculture, Food and Fisheries 2002). Reported from southern Idaho (Roche and Burrill 1996). Reported from Arizona, north of the Grand Canyon (Moser and Crisp, not dated). Some of the apparent increase in its range may be due to its being overlooked previously; Centaurea triumfettii is quite similar to widespread Centaurea species (Graham and Johnson 2004). However, it does seem to be increasing in the west.

11. Proportion of Potential Range Currently Occupied:Moderate significance
Comments: Inferred from USDA (1990) and Kartesz (1999), 10-30% of its potential generalized range in the U.S. is currently occupied.

12. Long-distance Dispersal Potential within Nation:Moderate significance
Comments: Recurved bracts on the seed heads cause them to cling to hair, wool, fur, clothing (Roche and Burrill 1996). Seeds are also dispersed by vehicles and equipment (Graham and Johnson 2004). Seeds are also transported when whole plants break off and tumble in the wind (Wilson and Randall 2003).

13. Local Range Expansion or Change in Abundance:High/Moderate significance
Comments: Centaurea triumfettii is very competitive and can displace native rangeland plants (British Columbia Ministry of Agriculture, Food and Fisheries 2002).

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Medium/Low significance
Comments: Occurs in dry open rangeland with shallow soils (Wilson and Randall 2003). In California, it occurs in disturbed places (Baldwin et al. 2004) and degraded juniper-shrub savanna (Roche and Burrill 1996). In Utah, it occurs on roadsides and other disturbed sites (Welsh 2003), big sagebrush-bunchgrass rangeland, salt desert shrub range, juniper-dominated rangeland, and crested wheatgrass rangeland (Roche and Burrill 1996). In Oregon, it has invaded juniper-Idaho fescue rangeland and big sagebrush-bunchgrass rangeland with cheatgrass (Roche and Burrill 1996). In Nevada, it occurs on roadsides, grain fields, and waste places (Kartesz 1988). Areas most susceptible to invasion in Nevada are sagebrush and pinion-juniper rangelands (Graham and Johnson 2004). Apparently, it usually occurs in areas with disturbance.

15. Similar Habitats Invaded Elsewhere:Insignificant
Comments: Not yet known from British Columbia or elsewhere in Canada (Kartesz 1999; British Columbia Ministry of Agriculture, Food and Fisheries 2002).

16. Reproductive Characteristics:Moderate significance
Comments: Produces more than 1000 seeds per plant (APRS Implementation Team 2001). Seeds remain viable in the soil for 1 to 5 years (APRS Implementation Team 2001). Stout taproots resprout making hand pulling ineffective (Roche and Burrill 1996).

Subrank IV. General Management Difficulty: High/Low

17. General Management Difficulty:High/Moderate significance
Comments: Large infestations can be treated with a combination of herbicides, improved grazing management, and revegetation with perennial forage species (Roche and Burrill 1996). Small recent infestations may be controlled by digging; the root should be cut at least eight inches below the soil surface to prevent the formation of new shoots (Graham and Johnson 2004). Stout taproots resprout making hand pulling ineffective (Roche and Burrill 1996). Seeds remain viable in the soil for 1 to 5 years (APRS Implementation Team 2001).

18. Minimum Time Commitment:Medium significance/Insignificant
Comments: Produces more than 1000 seeds per plant (APRS Implementation Team 2001). Seeds remain viable in the soil for 1 to 5 years (APRS Implementation Team 2001).

19. Impacts of Management on Native Species:High/Low significance
Comments: Herbicides may impact non-target species.

20. Accessibility of Invaded Areas:Low significance/Insignificant
Comments: The mature plant is unpalatable to grazing animals (Roche and Burrill 1996). Classified as a noxious weed in 3 western states (Kartesz 1999) and infestations are not in extreme or remote habitats; assumption is accessibility problems are not severe or substantial.
Authors/Contributors
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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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  • Alien plants ranking system (APRS) Implementation Team. 2001a. Alien plants ranking system version 7.1. Southwest Exotic Plant Information Clearinghouse, Flagstaff, AZ. Online. Available: http://www.usgs.nau.edu/swepic/ (accessed 2004).

  • Baldwin, B.G., S. Boyd, B.J. Ertter, D.J. Keil, R.W. Patterson, T.J. Rosatti and D.H. Wilken. 2004.
    Jepson Flora Project, Jepson Online Interchange for California Floristics. Regents of the University of California, Berkeley. Online. Available: http://ucjeps.berkeley.edu/jepson_flora_project.html (Accessed 2004).

  • British Columbia Ministry of Agriculture, Food and Fisheries. 2002. A Guide to Weeds in British Columbia. Victoria, British Columbia. Online. Available: http://www.weedsbc.ca/resources.html (accessed 2004).

  • Bureau of Land Management, Bishop Field Office. 2003. February 5 last update. Eastern Sierra Noxious Weeds. Online. Available: http://www.ca.blm.gov/bishop/weedlinks.html (accessed 2004).

  • California Exotic Pest Plant Council. 1999. The CalEPPC List: Exotic Pest Plants of Greatest Ecological Concern in California. Available: http://groups.ucanr.org/ceppc/Pest_Plant_List/. (Accessed 2004).

  • Colorado Weed Management Association (CWMA). 2000. Noxious weeds and non-native plant factsheets. Available: http://www.cwma.org/2_bad_weed.html. (Accessed 2004).

  • Graham, J., and W. S. Johnson. 2004. Managing Squarrose Knapweed, Fact Sheet FS-04-38. University of Nevada Cooperative Extension. Online. Available: www.unce.unr.edu/publications/FS04/FS0438.pdf (accessed 2004).

  • Kartesz, J.T. 1988. A flora of Nevada. Ph.D. dissertation. Univ. of Nevada, Reno. 3 volumes. 1729 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.

  • Moser, L., and D. Crisp. No date. San Francisco Peaks Weed Management Area fact sheet on Knapweed. Coconino National Forest. Available: http://www.usgs.nau.edu/SWEPIC/factsheets/knapweedssf_info.pdf. (Accessed 2004).

  • Ochsmann, J. 2003. April 23 last update. Knapweeds (Centaurea L. and some related genera) in North America. Online. Available: http://www.ochsmann.info/centaurea/centaurea-America.htm (accessed 2004).

  • Rice, P.M. 2004. February 19 last update. Invaders Database System. Division of Biological Sciences, University of Montana, Missoula. Online. Available: http://invader.dbs.umt.edu (accessed 2004).

  • RochC. and L.C. Burrill. 1996. Squarrose knapweed Centaurea virgata Lam. ssp. squarrosa Gugl., Pacific Northwest Extension Publication 422. Online. Available: eesc.orst.edu/agcomwebfile/edmat/pnw422.pdf (accessed 2004).

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

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  • USDA, ARS, National Genetic Resources Program. 2001. Germplasm Resources Information Network - (GRIN). [Online Database]. National Germplasm Resources Laboratory, Beltsville, Maryland.URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/taxon.pl?6438. (Accessed 2004)

  • Utah State Univserity. 1988. Atlas of the vascular plants of Utah, digital version of paper atlas authored by Beverly J. Albee, Leila M. Shultz, and Sherel Goodrich and published by the Utah Museum of Natural History. Online. Available: http://www.gis.usu.edu/Geography-Department/utgeog/utvatlas/index.html (accessed 2004).

  • Voss, E.G. 1996. Michigan Flora. Part III. Dicots (Pyrolaceae-Compositae). Cranbrook Institute of Science Bulletin 61 and Univ. Michigan Herbarium. Ann Arbor, Michigan. 622 pp.

  • Washington Native Plant Society (WNPS). 1997. Preliminary List of Exotic Pest Plants of Greatest Ecological Concern in Oregon and Washington. ONLINE. http://www.wnps.org/eppclist.html. Accessed 2004, January.

  • Welsh, S.L., N.D. Atwood, S. Goodrich and L.C. Higgins. (Eds.) 2003. A Utah Flora. 3rd edition. Brigham Young University, Provo, Utah, U.S.A. 912 pp.

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