Ptilostemon is a fine example of the representatives of the eastern groups of the Cardueae that have diversified in the western Mediterranean. Relationships to Cynara, which exhibits a similar ...

Strong, Ellen E. 2003. "Refining molluscan characters: morphology, character coding and the phylogeny of the Caenogastropoda (Gastropoda)." Zoological Journal of the Linnean Society, 137 447–554.