Carduus is a genus of flowering plants in the aster family,
Asteraceae, and the tribe
Cynareae, the
thistles. It is one of two genera considered to be "true thistles", the other being
Cirsium. Plants of the genus are known commonly as
plumeless thistles. They are native to Eurasia and Africa, and several are known elsewhere as
introduced species. This genus is noted for its disproportionately high number of
noxious weeds compared to other flowering plant genera.