Similar species: Field Thistle (Cirsium discolor) - A lot smaller overall. Hill's Thistle (Cirsium pumilum) - Fairly uncommon, a lot smaller overall. Nodding Thistle (Carduus nutans) - Flower is on a nodding head.
Plumeless Thistle (Carduus acanthoides) - Flowers are smaller, resemble those of Nodding Thistle (Carduus nutans) (except they are not nodding).
Swamp Thistle (Cirsium muticum) - A lot smaller overall.
PLEASE NOTE: A coloured Province or State means this species occurs somewhere in that Province/State.
The entire Province/State is coloured, regardless of where in that Province/State it occurs.
(Range map provided courtesy of the USDA website
and is displayed here in accordance with their
Policies)