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Montana Field Guide

Montana Field Guides

Eaton's Thistle - Cirsium eatonii
Other Names:  Cirsium tweedyi

Native Species

Global Rank: G4G5
State Rank: S4

Agency Status
MNPS Threat Rank:
C-value: 4

External Links

General Description
Taprooted perennial, often from a branched caudex. Stems erect, often unbranched, 10–70 cm. Herbage glabrate to arachnoid. Leaves short-petiolate; blade linear-lanceolate, 10–30 cm long with 10 to 20 pairs of shallow, closely-spaced lobes. Inflorescence capitate or spike-like with few, nearly sessile heads. Involucres broadly campanulate, 2–3 cm high, enclosed by uppermost leaves that obscure the phyllaries; phyllaries arachnoid especially on the margins, subequal in 4 to 5 series, green, linear-lanceolate; outer with spine-tips 7–10 mm long; inner acuminate. Disk corollas white, 17–23 mm long. Achenes 5–7 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Our plants are variety murdockii S.L. Welsh

Species Range

Range Comments
OR to MT south to NV, UT and NM (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 20

(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)


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Citation for data on this website:
Eaton's Thistle — Cirsium eatonii.  Montana Field Guide.  .  Retrieved on , from