Cirsium species

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These thistle species are grouped under White flowers, because of the overall appearance of the flower heads, even though the disk florets range from yellow to purple to brown. The IDs are believed to be correct but these can be highly variable species. One of the keys is their habitat.

Scientific Name Cirsium eatonii USDA PLANTS Symbol
CIEA
Common Name Eaton's Thistle, Mountaintop Thistle ITIS Taxonomic Serial No.
36365
Family Asteraceae (Sunflower) SEINet
Reference
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Description Life zones and habitat: Montane to alpine. Open areas.
Plant: Upright biennial/perennial, 24 to 48 inches tall.
Leaves: Hairless, oblong leaves 1/2 to 2 inches wide and 4 to 12 inches long, deeply lobed, with spines at the tip of each lobe.
Inflorescence: Spiny bracts around flower heads give white appearance to flowers, central disk florets pink to purple, no ray flowers.
References: Various.
Colorado Status
Native
Scientific Name Cirsium eatonii var. eriocephalum (Cirsium scopulorum) USDA PLANTS Symbol
CISC3
Common Name Alpine Thistle, Mountain Thistle, Frosty Ball ITIS Taxonomic Serial No.
780840
Family Asteraceae (Sunflower) SEINet
Reference
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Description Life zones and habitat: Subalpine and alpine. Open areas, windswept alpine ridges.
Plant: Upright perennial, 4 to 24 inches tall; stout, spiney stem.
Leaves: Basal and stem leaves, lanceolate up to 6 inches long, deeply incised with teeth tipped by spines 1/2-inch long.
Inflorescence: Clusters of very hairy flower heads, often nodding, with yellow ot pink/purplish disk florets in the centers, spiney bracts, no ray flowers.
References: Excerpts from "Guide to Colorado Wildflowers" by G.K. Guennel and SEINet.
Colorado Status
Native
Scientific Name Cirsium scariosum USDA PLANTS Symbol
CISC2
Common Name Meadow Thistle ITIS Taxonomic Serial No.
36143
Family Asteraceae (Sunflower) SEINet
Reference
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Description Life zones and habitat: Montane to subalpine. Meadows, moist open areas.
Plant: Upright biennial/perennial, 4 to 48 inches tall; fleshy, thick single or multiple stalks branched from near base.
Leaves: Basal and stem leaves, linear to elliptic 2 to 8 inches long, very wavy, shallow or deeply pinnately-dissected, hairy and spiney.
Inflorescence: One to many white to light lavender flower heads in a dense cluster, surrounded by pointed phyllaries with spines and teeth, and filled with many disk florets, no ray flowers.
References: Various.
Colorado Status
Native



© Tom Lebsack 2017