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     There are several dozen Thistles, native and introduced, in the Four Corners area.   Some of these Thistles reproduce from rhizomes; others are biennial, reproducing from seeds.  All are spiny and have only disk flowers.  Most Thistles are large and obvious in plant and in flower.  Some non-native Thistle are serious invaders of meadows and pastures.  

    The genus name, "Cirsium", is Greek for "dilated vein" from the bygone belief that a Thistle distillate opens clogged veins.  
Cirsium neomexicanum
Cirsium neomexicanum  (Thistle)
 Asteraceae (Sunflower Family)

Semi-desert, foothills. Shrublands, openings. Spring.
Above Yellow Jacket Canyon, Canyons of the Ancients National Monument, May 8, 2009.

Cirsium neomexicanum is quite similar to Cirsium tracyi which some consider the same as Cirsium undulatum.  Here is what A Utah Flora has to say about the relationship of C. neomexicanum to C. undulatum: C. neomexicanum "has long been confused with C. undulatum with which it shares the grayish tomentum, large heads, and tall stature.  They have been separated previously on the basis of glandular development of the dorsal ridge; a feature which is, unfortunately, not diagnostic".  This is just one more of many examples showing that what separates species is commonly not agreed upon by expert botanists.

Asa Gray named C. neomexicanum in 1853 from a specimen collected by Charles Wright in the Organ Mountains of southern New Mexico.
Cirsium neomexicanum
Cirsium neomexicanum  (Thistle)
 Asteraceae (Sunflower Family)

Semi-desert, foothills. Shrublands, openings. Spring.
Above Yellow Jacket Canyon, Canyons of the Ancients National Monument, May 8, 2009.

 
Cirsium neomexicanum
Cirsium neomexicanum  (Thistle)
 Asteraceae (Sunflower Family)

Semi-desert, foothills. Shrublands, openings. Spring.
Above Yellow Jacket Canyon, Canyons of the Ancients National Monument, May 8, 2009.

The cobwebby hairs at the base of the phyllaries on the surface of the involucre are a diagnostic characteristic of this species.  Notice that the spine-like tips are a different color from the much thicker and green base of the phyllaries.  Utah flora expert, Stanley Welsh, indicates that this is a primary characteristic separating two varieties of this species, this one being C. neomexicanum variety utahense and the other with involucral phyllaries green throughout being C. neomexicanum variety neomexicanum.
Cirsium neomexicanum

Cirsium neomexicanum  (Thistle)
 Asteraceae (Sunflower Family)

Semi-desert, foothills. Shrublands, openings. Spring.
Above Yellow Jacket Canyon, Canyons of the Ancients National Monument, May 8, 2009.

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 neomexicanum