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Montana Field Guide

Montana Field Guides

Squarrose Knapweed - Centaurea virgata
Other Names:  Squarrose Starthistle, Centaurea squarrosa

Non-native Species

Global Rank: GNR
State Rank: SNA

Agency Status
MNPS Threat Rank:
C-value: 1

External Links

General Description
Biennial to short-lived perennial. Stems erect, branched, 20–50 cm. Herbage puberulent to sparsely tomentose, glandular-punctate. Leaves petiolate below, the lowest deciduous; blades oblanceolate, 2–10 cm long, deeply pinnate into linear lobes. Inflorescence paniculate with numerous heads; peduncles short. Involucres ovoid, 6–9 mm high; outer phyllaries ovate, striate, tan, spreading spiny-margined; inner linear-lanceolate with scarious lacerate tips. Disk flowers 10 to 14, pink; the outer slender, 3-lobed; corollas 7–9 mm long, as long as the inner. Achenes glabrous, 2–3 mm long; pappus of short bristles, deciduous (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Range Comments
Introduced to OR and MT south to CA, NV, UT. Known from Jefferson and Lewis & Clark counties (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).


  • Literature Cited AboveLegend:   View Online Publication
    • Flora of North America Editorial Committee. 2006. Flora of North America North of Mexico. Vol. 19. Magnoliophyta: Asteridae, part 6: Asteraceae, part 1. Oxford Univ. Press, New York. xxiv + 579 pp.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
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Citation for data on this website:
Squarrose Knapweed — Centaurea virgata.  Montana Field Guide.  .  Retrieved on , from