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.

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

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  (Thistle)
Asteraceae (Sunflower Family)

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