Carduus nutans

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NOXIOUS WEED
CO, NM, UT

 This is a non-native highly invasive species.

Carduus nutans

Carduus nutans

Carduus nutans

Carduus nutans (Musk Thistle, Nodding Thistle)    
Asteraceae (Sunflower Family)

Semi-desert, foothills, montane, subalpine.  Meadows, disturbed areas.  Summer.
Top of page: Wildcat Canyon Trail, September 2, 2014.
Above: Priest Gulch Trail, September 4, 2013.

In the top photograph Betty has 9 foot Carduus nutans towering over her.

In the second photograph you can see Carduus nutans' dark purple pollen at the tips of the stamens.

The next photographs show a White-lined Sphinx Moth (Hyles lineata) enjoying Carduus nutans nectar with an amazingly long proboscis.

Carduus nutans

Carduus nutans (Musk Thistle, Nodding Thistle)    
Asteraceae (Sunflower Family)

Semi-desert, foothills, montane, subalpine.  Meadows, disturbed areas.  Summer.
Mesa Verde National Park, Knife Edge Trail, July 17, 2004 (with Zachary and Spencer).

Carduus nutans is a prickly, menacing, beautiful, common, foreign invader of lawns, farm fields, roadsides, and disturbed mountain fields.  It reproduces by seed which it produces prodigiously, resulting sometimes in a spiny, impenetrable thicket of Thistle.  As the photographs at the top of the page show, Carduus nutans can grow to enormous heights.

During its first year, Carduus nutans produces a basal rosette (sometimes several feet in diameter  --  see below) and in its second year it produces a stout, tall flower stalk armed with sharply pointed leaves. The plant then dies; it is a biennial.

To rid your property of this invasive species, do a thistle patrol several times during the summer and fall and use a shovel to cut the rosettes just below ground level. (I don't bother to pick up or bury the cut rosette. Keep it simple.) Some of the plants will die but others may produce a second or even third basal rosette. Cut the new rosettes and the plants will not continue into their second year of flowering. Probably one of the best times to attack the rosette is in the late fall when the plant will not have enough warmth and sunshine to produce a new rosette.

As the map at the bottom of the page shows, Carduus nutans is present in almost every county in Colorado, New Mexico, and Utah, yet in the 1960s it was hardly known at all in any of these states!  Stanley Welsh, Utah flora expert, indicates that the first Brigham Young University Herbarium collection is from 1967. H. D. Harrington's 1967 edition of the Manual of the Plants of Colorado indicates that Carduus nutans "has been reported in northeastern Arizona and may well be in Colorado".

Linnaeus named this genus and species in 1753.  "Cardu" is Latin for "Thistle" and "nutans" is Latin for "nodding", referring to nodding flowers, which are seldomly nodding in the Four Corners region.

Cadruss nutans

Carduus nutans (Musk Thistle, Nodding Thistle) 
Asteraceae (Sunflower Family)

Semi-desert, foothills, montane, subalpine.  Meadows, disturbed areas.  Summer.
Navajo Lake Trail, August 30, 2007.

Carduus nutans is a non-native species that can be a serious threat to native plants  --  but Carduus nutans flowers sure are gorgeous and thoroughly enjoyed by a number of insects.

Carduus nutans
Carduus nutans (Musk Thistle, Nodding Thistle) 
Asteraceae (Sunflower Family)

Semi-desert, foothills, montane, subalpine.  Meadows, disturbed areas.  Summer.
Near Yellowjacket Canyon, October 8, 2010.

A thick taproot produces a large, spreading, basal rosette of sharply armed leaves.  In the second year, this basal rosette will sprout a thick stem which will branch and produce many flowers, each of which will produce a prodigious number of seeds.

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

Carduus nutans

Range map for Carduus nutans