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Montana Field Guides

Musk Thistle - Carduus nutans
Other Names:  Nodding Plumeless-thistle, Nodding Thistle, Nodding 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 glabrate to villous. Leaves: basal wing-petiolate; blades oblanceolate, pinnately lobed, 6–20 cm long; cauline sessile, reduced upward. Inflorescence of solitary, sometimes nodding heads on spiny peduncles 2–30 cm long. Involucres 2–4 cm high; phyllaries lanceolate, outer reflexed; inner unarmed. Disk corollas 15–25 mm long. Achenes 4–5 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Diagnostic Characteristics
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.

Native versus Exotic (Source: Parkinson and Mangold 2015)
* Native thistles tend to have involucral bracts adhere to the flower head for most of their length (except for the spine).
* Native thistles tend to grow scattered across a habitat, spreading slowly with disturbance, and contribute to plant diversity.
* Exotic thistles grow quickly with disturbance, form dense patches that interferes with access, and through competition often reduces plant diversity.

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.

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.

Species Range
Montana Range

Non-native
 


Range Comments
Members of the genus Carduus are native to Europe and Asia. The first records of Carduus nutans (sensu latu) in North America are from Harrisburg, Pennsylvania, between 1853 and 1866 (Stuckey and Forsythe 1971), and from Chatham, New Brunswick in 1878 (Mulligan and Frankton 1954). The musk thistle complex has been found in at least 3068 counties in 40 of the mainland states, with 12% of those countries rating their infestation as "economic" (Dunn 1976). The present North American distribution extends from the east to west coast in the deciduous forest and prairie biomes, from Canada southward through the central states. In the east, in the Great Valley of the Appalachians, Ohio, Kentucky, and Tennessee, musk thistle is most commonly associated with soils derived from limestone (Stuckey and Forsythe 1971, Batra 1978). In the Great Plains and the West this relationship does not necessarily hold true (Batra 1978). The near-absence of members of the C. nutans group from the Great Basin and the Nebraska sandhills is probably attributable to its moisture requirements for germination. Within the Nebraska sandhills, musk thistle is found in pockets of finer-textured soil (Steuter pers. comm.).

Nursery studies of plants from throughout the United States suggest that Carduus thoermeri is the most widespread species of the group in both the United States and Canada. Carduus macrocephalus is the dominant species in Montana and the intermountain region and Carduus sp. (unnamed) is restricted to British Columbia (McCarty 1985).


Observations in Montana Natural Heritage Program Database
Number of Observations: 8596

(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
Fields, roadsides, disturbed grasslands, riparian meadows; valleys, montane (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

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 "Musk Thistle"
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Citation for data on this website:
Musk Thistle — Carduus nutans.  Montana Field Guide.  .  Retrieved on , from