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  • canada
  • Native species of Cirsium range from sea level to alpine and from boreal regions of Canada to the tropics of Central America. (efloras.org)
  • stem
  • Stout, short-lived perennial from a taproot, this sometimes branching below-ground and producing more than one stem, but without the well developed creeping roots of no. 9 [Cirsium flodmanii (Rydb. (vplants.org)
  • native
  • I have seen no documentation of hybridization between native American Cirsium species and introduced Eurasian taxa. (efloras.org)
  • North American
  • Although there has been a remarkable evolutionary and morphologic diversification in North American Cirsium , it has not been accompanied by very much divergence in the base sequences of genes commonly used to elucidate phylogenetic relationships. (efloras.org)
  • This suggests either that the diversification has been very rapid or that genetic markers in North American Cirsium mutate more slowly than in most other lineages. (efloras.org)
  • Chromosomal diversification has accompanied the morphologic radiation of North American Cirsium . (efloras.org)
  • base
  • Many New World Cirsium species share the chromosomal base number of x = 17 that also predominates in most Eurasian species. (efloras.org)