Only two concern about the shape of involucral bracts that in C. orientalis have a clearly cliliate margin in their appendix and that online databases don't report this species for Greece. Sice O. orientalis is reported for eastern europe, storm will surely know if this determination can be taken on account or not. Bye
Valerio, thank you for suggestion. But Centaurea orientalis have mostly solitary heads in different habitats Link unless it is not a hybrid with Centaurea apiculata: Link , Link
The photos from your site are very explanative of what is the real habitus of O. orientalis. What can I say? That we need a manual of the greek flora or some greek botanist! Ciao