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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.  

Below you will find photographs of Cirsium eatonii and Cirsium scopulorum.

However, John Kartesz indicates that Cirsium eatonii is not found in the Four Corners region; it is a species found farther west. (See the maps below.) Kartesz indicates that our plant in the Four Corners region is properly called Cirsium scopulorum and that Cirsium eatonii variety hesperium is a synonym for C. eatonii.

The Flora of North America indicates that C. eatonii variety hesperium is found in our area and that Cirsium eriocephalum is a synonym for Cirsium eatonii variety hesperium.

Welsh, Weber, and Ackerfield indicate that both Cirsium scopulorum and Cirsium eatonii are found in the Four Corners region.

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

Cirsium eatonii

Cirsium eatonii

Cirsium eatonii (Eaton's Thistle)
Asteraceae (Sunflower Family)

Montane, subalpine, and alpine.  Openings, scree. Summer. 
Above and left: Grand Mesa, July 11, 2017.

Cirsium eatonii can grow to a spiny 4.5' tall (more commonly, 3.5' as shown here). Flower heads are numerous, large, showy, usually upright, sessile, and commonly a light pink to white. A few thin bract-like leaves appear to be upward stretched arms at the side of the flower heads.

As the second photograph shows, only spiny phyllary tips protrude through a mass of cobwebby hairs. The phyllary surface cannot be seen.

Flower color can be white to pink.

This species was at first named Cirsium eriocephalum var. leiocephalum in 1871 by Daniel Eaton who collected it with Sereno Watson. It was renamed Cnicus eatoni by Asa Gray in 1883 and then given its present name in 1911 by B. L. Robinson.

Daniel Eaton was a Professor of Botany at Yale and a well respected plant collector. (Click for more biographical information about Eaton.)

Cirsium eatonii

Cirsium eatonii (Eaton's Thistle)
Asteraceae (Sunflower Family)

Montane, subalpine, and alpine.  Openings, scree. Summer.  
Grand Mesa, July 11, 2017.

Stems are red to green and hairy. Notice the glow of hairs at the side of the stems.

Leaves are narrow deeply cut (but not all the way to the center vein) and spiny.

 

Cirsium scopulorum
Cirsium eatonii variety hesperium
Cirsium scopulorum. Synonyms: Cirsium hesperium, Cirsium eriocephalum, Cirsium eatoni var. hesperium, Cirsium eatoni var. eriocephalum. (Alpine Thistle)
Asteraceae (Sunflower Family)

Subalpine and alpine.  Openings, scree. Summer. 
Above and left: Stony Pass above Silverton, July 26, 2017 and 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, often nodding. 

John Kartesz indicates that Cirsium eatonii is a species found farther west than the Four Corners region. (See the maps below.) Kartesz indicates that our plant in the Four Corners region is properly called Cirsium scopulorum and that Cirsium eatonii variety hesperium is a synonym for C. eatonii.

The Flora of North America indicates that the species is C. eatonii variety hesperium and that Cirsium eriocephalum is a synonym for Cirsium eatonii variety hesperium.

Welsh, Weber, and Ackerfield indicate that both C. scopulorum and C. eatonii are found in the Four Corners region.

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. Synonyms: Cirsium hesperium, Cirsium eriocephalum, Cirsium eatoni var. hesperium, Cirsium eatoni var. eriocephalum. (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. Synonyms: Cirsium hesperium, Cirsium eriocephalum, Cirsium eatoni var. hesperium, Cirsium eatoni var. eriocephalum. (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 eatonii

White indicates the range of Cirsium eatonii according to local botanists,
but Kartesz uses white to indicate "False Reports", i.e., what was previously
reported as Cirsium eatonii in these counties is now considered to be a
different Cirsium species, most probably Cirsium scopulorum.

Cirsium eatonii

Range map for all varieties of Cirsium eatonii according to Kartesz.

Cirsium scopulorum

Range map for Cirsium scopulorum