creeping thistle, Cirsium arvense
Seed from Cirsium arvense was inadvertently imported from Europe to North America in the early 1600s; it tagged along in bags of grain seed. The plant received its current common name — in North America — when it appeared alongside grain crops in what is now called New England. The grain seed had been imported from Canada. Hence, those early settlers thought the thistle came from Canada.
Elsewhere the plant called Canada thistle has many names:
Lettuce From Hell Thistle, Corn Thistle, Cursed Thistle, Field Thistle, Green Thistle, Hard Thistle, Perennial Thistle, Prickly Thistle, Small-flowered Thistle and Way Thistle.
The most used common name in Europe, where it comes from, is creeping thistle.
The trouble with the Canadian appellation for this invasive introduced plant is that uninformed people may construe that it is a North American Native. But, IT'S NOT! However, being perceived as such gives Native plants a bad rap, especially since most people don't want Canada ... ah ... creeping thistle around.
I don't know how plant names get changed or who determines such things but henceforth I plan to refer to Cirsium arvense as creeping thistle.
Robert G Mears