Cirsium undulatum is a species of thistle known by the common names wavyleaf thistle and gray thistle. It is native to much of central and western North America from British Columbia east to Manitoba and south as far as the State of Durango in Mexico. It has also been found outside of its native range as an introduced species.Cirsium undulatum is widespread and found in many habitat types. It is a perennial herb exceeding 200 cm (79 in) in height. The stem branches a few times toward the top of the ...