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Montana Field Guide

Montana Field Guides

Spiny-leaf Sowthistle - Sonchus asper
Other Names:  Rough Milk Thistle, Sharp-fringed Sow Thistle, Prickly Sow Thistle, Spiny Sowthistle

Non-native Species

Global Rank: GNR
State Rank: SNA

Agency Status
MNPS Threat Rank:
C-value: 0

External Links

General Description
Taprooted annual. Stems erect, 25–90 cm tall, simple or branched. Leaves oblong to oblanceolate, pinnately toothed or lobed less than halfway to the midvein, 5–20 cm long, winged-petiolate below, auriculate-clasping above. Involucres 8–14 mm high; phyllaries glabrous. Ray ligules 3–5 mm long, inconspicuous. Achenes tan to red-brown, 2–3 mm long, smooth between the ribs (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Montana Range


Range Comments
Introduced from Eurasia; in nearly all of North America except the Canadian high arctic.

Observations in Montana Natural Heritage Program Database
Number of Observations: 31

(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)

Disturbed soil of roadsides, pastures, lawns, streambanks; plains, valleys (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

  • 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.
    • Zapatka, T.P. 1963. Some results of two limited hunting seasons on hen Pheasants in north central Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 26 p.
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Citation for data on this website:
Spiny-leaf Sowthistle — Sonchus asper.  Montana Field Guide.  .  Retrieved on , from