Cirsium hookerianum

{{Short description|Species of thistle}}

{{Speciesbox

| image = Hooker's Thistle imported from iNaturalist photo 410065158 on 16 October 2024.jpg

| image_caption =

| genus = Cirsium

| species = hookerianum

| authority = Nutt.

| synonyms_ref = [http://www.theplantlist.org/tpl1.1/record/gcc-129336 The Plant List, Cirsium hookerianum Nutt. ]

| synonyms =

• Carduus hookerianus (A.Gray) A.Heller
• Cnicus hookerianus A.Gray

}}

Cirsium hookerianum, Hooker's thistle or white thistle, is a North American species of thistle native to western Canada and the northwestern United States. It is found in the northern Rocky Mountains as well as in some of the northern Cascades and Coast Ranges, in Alberta, British Columbia, Washington, Idaho, Montana, and Wyoming.[http://bonap.net/MapGallery/County/Cirsium%20hookerianum.png Biota of North America Program 2014 county distribution map]

Cirsium hookerianum is biennial or perennial herb up to 150 cm (60 inches) tall, with a large taproot. Leaves are green on top, usually white and woolly underneath, with spines along the edges. There are usually several flower heads with white or pink disc florets but no ray florets. The species grows in grasslands, meadows, and the edges of forests in mountainous areas.[https://www.biodiversitylibrary.org/page/36318139#page/440/mode/1up Nuttall, Thomas 1841. Transactions of the American Philosophical Society, new series 7: 418–419][http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250066375 Flora of North America, Hooker’s or white thistle, Cirsium hookerianum Nutt.]