Cirsium scariosum (Poir.) Nutt., “Trans. Amer. Philos. Soc. ser. 2, 7” 420 1841. (Syn: Carduus americanus (A.Gray) Greene; Carduus tioganus (Congdon) A.Heller; Cirsium drummondii var. lanatum Petr.; Cirsium drummondii subsp. lanatum Petr.; Cirsium drummondii var. vexans Piper; Cirsium hookerianum var. scariosum (Nutt.) B.Boivin; Cirsium minganense f. album Vict. & J.Rousseau; Cnicus scariosus A.Gray; Carduus butleri Rydb.; Carduus lacerus Rydb.; Carduus magnificus A.Nelson; Cirsium butleri (Rydb.) Petr.; Cirsium lacerum (Rydb.) Petr.; Cirsium magnificum (A.Nelson) Petr.; Cirsium minganense Vict.);
Cirsium scariosum is a species of thistle known by the common names meadow thistle and elk thistle.
It is native to much of western North America from Canada to Mexico, where it grows in a variety of habitat types.
This is a variable species made up of several geographic races, most of which have been previously classified as species. The races intergrade but their morphologies can also be quite different.
This is generally a biennial or perennial herb. It takes three main forms, a stemless, flat rosette with a cluster of flower heads in the center, a mounding form with a short, erect stem, or a fully erect form reaching up to 2 meters in height. When there is a stem it is usually fleshy, ridged, and woolly in texture. The leaves are sharply toothed or cut into toothed lobes, lined with spines, and up to 40 centimeters at their longest near the base of the plant. The inflorescence holds several flower heads, each up to 4 centimeters long and 5 wide. The flower head is lined with phyllaries which may have spines and teeth and filled with white to purple flowers. The fruit is a compressed achene a few millimeters long topped with a pappus which may be 3 centimeters in length.
(From Wikipedia on 15.6.13)
Asteraceae Fortnight Part 2-Discoid heads- Cirsium scariosum from California-GS32 : Attachments (2). 4 posts by 3 authors.
Cirsium scariosum photographed from Shasta mountains in California.
It was 6 July …
Asteraceae Fortnight Part 2-Discoid heads:: Plant for ID SMP 22 Yellowstone USA : Attachments (2). 3 posts by 2 authors.
Cirsium scariosum Nutt. is correct Id.
To me it does not look like C. scariosum, leaves are different.
Cirsium scariosum from Shasta, California-GS04012022-4: 4 high res. images.
Common names: Shasta valley thistle, Sessile thistle
This variable species is often stemless, with usually sessile flowerheads, pale pink to white
Photographed from Shasta Mountains, California, 26-7-2008
The Plant List 1 The Plant List 2 GRIN Flora of North America Wikipedia Swcolarado