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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 Cirsium genus was named by Philip Miller (1691-1771). "Cirsium", is Greek for "dilated vein" from the bygone belief that a Thistle distillate opens clogged veins.  

Cirsium eatonii variety hesperium
Cirsium scopulorum. Synonym: Cirsium eatonii variety hesperium. (Alpine Thistle)
Asteraceae (Sunflower Family)

Subalpine and alpine.  Openings, scree. Summer. 
Stony Pass above Silverton, July 17, 2010.

This very prickly native Thistle grows 20-60 inches tall at maturity.  The plant usually has a very erect posture with narrow, often hairless, shiny leaves and tight clusters of very attractive flowers. 

The Flora of North America indicates that the species is C. eatonii variety hesperium, and Allred's Flora Neomexicana III agrees with that name. But the Flora of North America observes, "Variety hesperium is distributed [only] in the San Juan Mountains and Spanish Peaks area of southern Colorado."

John Kartesz, the ultimate authority for names on this web site, indicates that C. eatonii is an incorrect name for the species in our area, and Kartesz indicates that our plant in the Four Corners region is properly called Cirsium scopulorum, a name that Welsh, Weber, Ackerfield, and Heil & O'Kane agree with. Kartesz indicates that C. eatonii is a species found farther west than the Four Corners region. (See the maps below.)

From a collection made on alpine ridges in the headwaters of Clear Creek, Colorado, in 1861 by Charles Parry, C. scopulorum was first named Cirsium eriocephalum by Asa Gray in 1864. It was then named Carduus eriocephalum by Edward Greene in 1893 and in 1911 Cockerell named the plant C. scopulorum.

"Scopulorum" means "of rocky places", an apt name for this species, as the photographs show.

Cirsium eatonii variety hesperium

Cirsium eatonii variety hesperium

Cirsium scopulorum. Synonym: Cirsium eatonii variety hesperium. (Alpine Thistle)
Asteraceae (Sunflower Family)

Subalpine and alpine.  Openings, scree. Summer. 
Stony Pass above Silverton, July 17, 2010.

Flower color can range from white to yellow to pink to purple.

Cirsium eatonii variety hesperium

Cirsium scopulorum. Synonym: Cirsium eatonii variety hesperium. (Alpine Thistle)
Asteraceae (Sunflower Family)

Subalpine and alpine.   Openings, scree. Summer. 
Stony Pass above Silverton, July 17, 2010.

Leaves are narrow, to 35 cm long, prominently spiny edged, and may be glabrous or hairy.

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

Cirsium scopulorum

Range map for Cirsium scopulorum

Cirsium eatonii

Range map for all varieties Cirsium eatonii