Cirsium coloradense
(Colorado Thistle)
Cirsium coloradense, Middle Swan River, Summit Co. 5611
Cirsium coloradense, Middle Swan River, Summit Co. 5608
Cirsium coloradense, Middle Swan River, Summit Co. 5599
| Scientific Name | Cirsium coloradense (Cirsium scariosum var. coloradense) | USDA PLANTS Symbol | CISC2 |
| Common Name | Colorado Thistle | ITIS Taxonomic Serial No. | 780757 |
| Family | Asteraceae (Sunflower) | SEINet Reference |
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| Description |
Life zones and habitat: Montane to subalpine (7000 to 12500 ft.); moist open areas; meadows, along streams and roadsides. Plant: Erect biennial or short-lived perennial 12 to 40 inches tall; fleshy, thick single or multiple stalks branched from near base with soft spines. Leaves: Basal and stem leaves, linear to elliptic 4 to 16 inches long, very wavy, shallow or deeply pinnately-lobed with a broad central midstrip; sessile; smooth above and woolly-hairy below; spiney. Inflorescence: Dense clusters of one to many flower heads with no ray florets; white to light lavender disk florets 3/4 to 1-3/8 inches long; many long, sharp-pointed phyllaries with spines growing beyond the corolla. Bloom Period: June to September. References: "Flora of Colorado" Second Edition by Jennifer Ackerfield, Cirsium scariosum var. coloradense in iNaturalist and in Flora of North America. Note: In the research document Thistle be a mess: Untangling the taxonomy of Cirsium (Cardueae: Compositae) in North America by Ackerfield, et al, C.scariosum var. coloradense becomes C. coloradense. |
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