https://www.pollenlibrary.com/Local/Specie/Carduus+nutans/in/Butler%20County/OH/
Nodding Plumeless-Thistle (Carduus nutans) Species Details and Allergy Info, Butler county, Ohio
Carduus nutans Research Information. Nodding Plumeless-Thistle allergy information and photos, Butler county, Ohio
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https://minnesotawildflowers.info/flower/nodding-thistle
Carduus nutans (Nodding Thistle): Minnesota Wildflowers
Photos and information about Minnesota flora - Nodding Thistle: 2 to 3-inch purple to magenta flower heads that often nod down
carduus nutansnodding thistleminnesota wildflowers