Bull thistle or field thistle not sure.
Canada Thistle has become the most wide spread invasive weed in North Dakota.
Long lived perennial with an extensive root system that can grow laterally 12-15 feet per year.
Leaves are oblong, usually deeply cut and have spiny-toothed edges.
Flowers range from purple to rose and sometimes white. Male and female flowers are produced on different plants.
Canada thistle was listed in 1885 by Dakota Territory as "required of every person to destroy this weed."
Cirsium is a genus of perennial and biennial flowering plants in the Asteraceae, one of several genera known commonly as thistles. They are more accurately known as Plume thistles. These differ from other thistle genera (Carduus, Silybum and Onopordum) in having feathered hairs to their achenes. The other genera have a pappus of simple unbranched hair.