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Montana Field Guide

Montana Field Guides

Spiny Plumeless-thistle - Carduus acanthoides
Other Names:  Plumeless Thistle, Welted Thistle

Non-native Species

Global Rank: GNR
State Rank: SNA

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

External Links






 
General Description
Stems 30–150 cm. Herbage sparsely villous on midveins. Leaves: basal wing-petiolate; blades oblanceolate, deeply pinnately lobed, 10–20 cm long; cauline sessile, reduced upward. Inflorescence with several erect heads on spiny stems; peduncles 1–2 cm long. Involucres 14–20 mm high; phyllaries linear-lanceolate, appressed, the outer spine-tipped, inner purple, long-attenuate. Disk corollas 12–20 mm long. Achenes 2–3 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Phenology
On first-glance thistles can look similar, but upon closer inspection differences become apparent.
Thistles belong to the genera of Cirsium, Carduus, and Onopordum. They are separated by:

Cirsium
* Feathery (plumose) pappus, which have fine, long hairs on each side of the main bristle.
* Receptacle of flower head has bristles. Look between florets within a flower head to find them.

Carduus
* Capillary pappus, which are minutely barbed, narrow bristles.
* Receptacle of flower head has bristles. Look between florets within a flower head to find them.

Onopordum
* Receptacle of flower head has no bristles. Look between florets within a flower head to find nothing.
* Entire lengths of stems have spiny wings.
* Foliage is silvery gray.

Spiny Plumeless Thistle - Carduus acanthoides, exotic and undesirable
* Flower heads are several per stem and have involucres are less than 2 cm tall.
* Flower heads have involucral bracts that are narrowly triangular (less than 2mm wide), have smooth margins, and a short spine-tip.
* Heads nod as flowers mature.

Musk Thistle - Carduus nutans, exotic and undesirable
* Flower heads are mostly solitary and have involucres of 2-4 cm tall.
* Flower heads have involucral bracts that are broadly triangular (more than 2mm wide), have smooth margins, and a short spine-tip.
* Heads nod as flowers mature.

Species Range
Montana Range

Non-native
 


Range Comments
Introduced to northern U.S. (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 318

(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

Management

References
  • Literature Cited AboveLegend:   View Online Publication
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Parkinson, Hilary and Jane Mangold. 2015. Guide to Exotic Thistles of Montana and How to Differentiate from Native Thistles. EB0221. Montana State University Extension, Bozeman, Montana.
  • Web Search Engines for Articles on "Spiny Plumeless-thistle"
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Citation for data on this website:
Spiny Plumeless-thistle — Carduus acanthoides.  Montana Field Guide.  .  Retrieved on , from