• Flora
  • After consulting with A. Cronquist and studying his manuscript treatment of Cirsium for the Intermountain Flora , D. J. Keil and C. E. Turner (1993) also accepted a broadly construed C. scariosum . (swbiodiversity.org)
  • base
  • 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)
  • field
  • In other cases hybridization has been invoked without much evidence as an explanation for Cirsium variants encountered in herbaria or in the field. (efloras.org)