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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 scariosum
Cirsium scariosum variety coloradense.  Synonym: Cirsium coloradense. (Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows. Summer.
Lone Mesa State Park, August 4, 2008.

Cirsium scariosum can be six feet tall or have no stem and lie plastered to the ground.  It is a distinct Thistle because of this growth habit, its stemless flowers tucked into the leaf axils, and its very light green leaves and stems.

Cirsium scariosum was first collected for science by Thomas Nuttall in Idaho in the 1830s and was named by Nuttall in 1841.  According to Michael Charter's on-line dictionary of botanical names, "scariosum" is for " 'scarious', [meaning] shriveled, thin, dry, often translucent and not green" and probably refers to the very light leaf and stem color and/or to the scarious tips of the phyllaries.

Cirsium scariosum variety coloradense.  Synonym: Cirsium coloradense. (Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows. Summer.
Lone Mesa State Park, August 4, 2008.

Cirsium scariosum
Cirsium scariosum variety coloradense.  Synonym: Cirsium coloradense. (Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows. Summer.
Lone Mesa State Park, August 4, 2008.

The arrow points to the phyllaries which are flattened, glabrous or with some cobwebby hairs, and tipped with spines. The spines are brown at their base where they are turned outward at a ninety degree angle from the light green bodies of the numerous phyllaries.

 

Cirsium scariosum
Cirsium scariosum variety coloradense.  Synonym: Cirsium coloradense. (Thistle)
Asteraceae (Sunflower Family)

Foothills, montane. Meadows. Summer.
Lone Mesa State Park, August 15, 2008.

Mature flowers have exploded in a mass of fluff that will carry the seeds on fall winds.

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 scariosum