| Popis: |
Morphological descriptions, chromosome numbers, and Canadian distribution of Cirsium muticum and C. discolor are given. The related species C. altissimum of the United States is similarly considered. The chromosome numbers of the species are: C. muticum, 2n = 20; C. discolor, 2n = 20; C. altissimum, 2n = 18. Extra chromosomes, possibly to be considered as accessories, were found in C. muticum and C. discolor. A Florida collection of C. muticum had the apparently triploid number 2n = 30. The morphological and cytological evolution of the group is discussed. |
