2 species and one hybrid in WI; 5 in US & Canada; 90 worldwide.
Introduced from Eurasia and Africa.
Spiny-leaved herbs closely resembling Cirsium, but distinguished by the non-plumose, capillary pappus.
Johnson, M.E. and H.H. Iltis. 1963. Preliminary reports on the flora of Wisconsin: No. 48. Compositae Family. Wisconsin Academy of Sciences, Arts & Letters. 52:255-342.