Cirsium scopulorum

(Mountain-top Thistle)

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Cirsium scopulorum, Loveland Pass, Clear Creek Co. 1567

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Cirsium scopulorum, Loveland Pass, Clear Creek Co. 1561

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Cirsium scopulorum, Loveland Pass, Clear Creek Co. 1596

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Cirsium scopulorum, Loveland Pass, Clear Creek Co. 1597

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Cirsium scopulorum, Loveland Pass, Clear Creek Co. 1576

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Cirsium scopulorum, Loveland Pass, Clear Creek Co. 2883

Scientific Name Cirsium scopulorum (Cirsium eatonii var. eriocephalum) USDA PLANTS Symbol CISC3
Common Name Mountain-top Thistle, Alpine Thistle ITIS Taxonomic Serial No. 780840
Family Asteraceae (Sunflower) SEINet
Reference
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Description Life zones and habitat: Subalpine and alpine (10500 to 13500 ft.); open areas, tundra, scree, meadows, windswept alpine ridges.
Plant: Upright perennial, 8 to 32 inches tall; stout, spiney stem.
Leaves: Basal and stem leaves, lanceolate 1 to 13 inches long, deeply pinnately-incised with lobes tipped by spines 1/2-inch long; smooth above, woolly-hairy below.
Inflorescence: Densely-packed clusters of often nodding, very hairy flower heads that can extend on the stem nearly to ground level; light pink to purple disk florets in the center; no ray flowers; involucres with very white, densely-hairy, spiney phyllaries 3/8 to 3/4-inch long.
Bloom Period: July to September.
References: "Flora of Colorado" Second Edition by Jennifer Ackerfield, "Guide to Colorado Wildflowers" by G.K. Guennel and SEINet.
Note: In the research document Thistle be a mess: Untangling the taxonomy of Cirsium (Cardueae: Compositae) in North America by Ackerfield, et al, C.eatonii var. eriocephalum becomes C. scopulorum.
BONAP Distribution Map


Map Color Key
Colorado Status:
Native

© Tom Lebsack 2024

Banner photo: Castilleja rhexifolia and a brewing storm over the San Juan Mountains