Cirsium canescens

(Prairie Thistle)

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Cirsium canescens, Pawnee Buttes, Weld Co. 7732

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Cirsium canescens, Pawnee Buttes, Weld Co. 7758

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Cirsium canescens, Pawnee Buttes, Weld Co. 7738

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Cirsium canescens, Pawnee Buttes, Weld Co. 7755

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Cirsium canescens, Pawnee Buttes, Weld Co. 7745

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Cirsium canescens, Pawnee Buttes, Weld Co. 7750

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Cirsium canescens, Pawnee Buttes, Weld Co. 7747

Scientific Name Cirsium canescens USDA PLANTS Symbol CICA11
Common Name Prairie Thistle ITIS Taxonomic Serial No. 36350
Family Asteraceae (Sunflower) SEINet
Reference
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Description Life zones and habitat: Plains to montane (3500 to 9500 ft.); sandy or gravelly soils on prairies and in disturbed areas, and in mountain meadows and coniferous forests.
Plant: Upright biennial, 16 to 32 inches tall.
Leaves: Oblong to elliptic or obovate leaves 3/4 to 2-3/8 inches wide and 4 to 10 inches long (upper leaves reduced), deeply pinnatifid, with spines at the tip of each lobe; blue-green in color; very hairy (cob-webby) above, densely woolly-hairy below.
Inflorescence: Open arrays (corymbs or racemes) of 1 to 10 or more flower heads; central disk florets are white or lavender-tinged, 3/4 to over 1 inch long; no ray flowers; involucre phyllaries with yellow upward- and outward-pointing spines on tips of outer row, with a whitish glutinous ridge below each tip.
Bloom Period: June to September.
References: "Flora of Colorado" by Jennifer Ackerfield, SEINet and "Thistles of Colorado" by Larimer County Weed Distict.
BONAP Distribution Map

Colorado Status:
Native

© Tom Lebsack 2022

Banner photo: Ten Mile Range and Rhodiola integrifolia (King’s Crown) in Summit County