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Montana Field Guide

Montana Field Guides

Spotted Knapweed - Centaurea stoebe
Other Names:  Centaurea biebersteinii, Centaurea maculosa

Noxious Weed: Priority 2B
Exotic Species (not native to Montana)

Global Rank: GNR
State Rank: SNA

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 0

External Links






 
General Description
Perennial. Stems erect, branched, 25–100 cm. Herbage sparsely tomentose, glandular-punctate. Leaves long-petiolate below; blades ovate, 3–12 cm long, deeply pinnately 1 to 2 times divided into linear-oblanceolate lobes. Inflorescence corymbiform with several heads. Involucres ovoid, 8–13 mm high; phyllaries green, striate, sparsely glandular; the outer ovate with white to brown fringed tips; inner lanceolate with swollen tips. Disk flowers 30 to 40, rose-purple (white); the outer enlarged, asymmetrical; inner corollas 12–15 mm long. Achenes 3–4 mm long; pappus of deciduous, stiff bristles (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Lesica (2012) treats this as C. maculosa Lam. Ours is subspecies micranthos, a tetraploid perennial which has been introduced across North America.

Diagnostic Characteristics
This species readily hybridizes with Centaurea diffusa. These fertile hybrids have been named Centaurea x psammogena.

Species Range
Montana Range

Click the legend blocks above to view individual ranges.
 


Range Comments
Introduced throughout temperate N. America (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 32989

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

Recency

 

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



Habitat
Grasslands, roadsides, meadows, open forest, woodlands; plains, valleys, montane (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

References
  • Additional ReferencesLegend:   View Online Publication
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    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Willard, E.E., D.J. Bedunah, and C.L. Marcum. 1988. Impacts amI potential Impacts opf spotted knapweed (Centaurea maculosa) on forest and range lands in western Montana. Unpubl. Rep., Montana For. and Conserve Exp. Sta., University of Montana, Missoula.
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Citation for data on this website:
Spotted Knapweed — Centaurea stoebe.  Montana Field Guide.  .  Retrieved on , from