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NOXIOUS WEED
CO, NM, UT

Cirsium arvense

Cirsium arvense. Synonym: Breea arvensis.  (Canada Thistle, Creeping Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, disturbed areas.  Summer.
Near Yellow Jacket Canyon, August 3, 2005.

Over 200 years ago, Frederick Pursh said of Cirsium arvense in his Flora Americae Septentrionalis, "It is one of the most troublesome weeds, and when once introduced on a plantation it is almost impossible to get rid of it". Read about the characteristics of this highly successful invasive plant. And read more. Controlling Cirsium arvense.

Cirsium arvense spreads easily (far too easily!) by both seed and root and it is, therefore, very difficult to exterminate.  Using herbicides (which I won't do) or cutting off the above ground stem every few days are two methods used for decades to remove this noxious weed -- and these two methods don't work completely either. Biological controls have been used on several continents, but, in the words of one evaluation of these, "We conclude that the potential of pathogens for biocontrol of Cirsium arvense has largely been overestimated". However, the pathogen Puccinia punctiformis has become more and more common on my property and is successful at stopping Cirsium arvense from flowering and actually killing plants. See the last photographs on this page.

I am trying to attack small sections of Cirsium arvense on my property by pulling each of the taller plants with two hands, and I find that even if the ground is dry, I can get 5-8 inches of the root. Then when the plant resprouts I pull off the new green. If one keeps at this, the root system will be exhausted. If plants have gone to seed, I am careful to bag the plant for the garbage.

Leaves of Cirsium arvense are very prickly; flower heads are attractive, numerous, and very pleasantly sweet smelling; and seed production is enormous.  Flowers are unisexual and usually only male or female flowers occur on each plant.

"Serratula arvensis" was the name Linnaeus gave this plant in 1753 Linnaeus. It is a native of Eurasia, probably first from southeastern Europe. It was renamed "Cirsium arvense" (its most widely accepted name today) in 1772.  Breea arvensis, the name which William Weber accepts, was given in 1832.

"Arvense" is Latin for "of fields", and "Breea" honors William Thomas Bree, botanist and theologian(More biographical information about Bree.)

Cirsium arvense

Cirsium arvense

Cirsium arvense. Synonym: Breea arvensis.  (Canada Thistle, Creeping Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, disturbed areas.  Summer.
Near Yellow Jacket Canyon, August 26, 2005 and October 8, 2010.

The leaves of Cirsium arvense are narrow, deeply notched, and armed with numerous spiny tips.  It is common for basal rosettes of leaves to occur in clusters.

Cirsium arvense

Cirsium arvense

Cirsium arvense. Synonym: Breea arvensis.  (Canada Thistle, Creeping Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, disturbed areas.  Summer.
Near Yellow Jacket Canyon, August 3, 2005.

Minute flowers are numerous, as are the seeds and pappus hairs. In a manner quite uncommon for Asteraceae, the pappus hairs of Cirsium arvense commonly detach from the seeds before carrying them away on the winds. Seeds then drop near the parent plant.

Cirsium arvense

Cirsium arvense. Synonym: Breea arvensis.  (Canada Thistle, Creeping Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, disturbed areas.  Summer.
Near Yellow Jacket Canyon, July 29, 2020.

Puccinia punctiformis has killed the Cirsium arvense plant at left. The underside of leaves is dotted with individual rust spots and with larger collections in black masses. This naturally occurring pathogen occurs on my property and on other acerage in Montezuma County, Colorado. Agricultural agents are actively spreading P. punctiformis in the county.

Click for more details about P. punctiformis.

Another Puccinia, P. monoica, attacks native wildflower species. See Boechera.

               Cirsium arvense

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Cirsium arvense