The phytogeography of Rodhos is briefly sketched. The flora of Rodhos holds a dual position having affinities with the S Aegean islands as well as with the E Aegean islands and SW Anatolia. The present distribution of species on Rodhos corresponds with the palaeogeographic history of the area.
Differentiation has apparently taken place in several taxa since the separation of Rodhos from the S Aegean islands and SW Anatolia, which is shown by the occurrence of many allopatric taxa. The occurrence of many local variants without taxonomic rank shows that this process of speciation is still not complete. Areas of ophiolithic rock are shown to influence the species composition, since many species avoid or are more or less restricted to these areas. Many taxa of the ultrabasic areas show at least a slight morphological distinction from non-serpentine populations of the same species, and some are distinctive enough to recognise at species rank. Both these areas of ophiolithic rock and the limestone cliffs have apparently provided refugia for taxa with formerly wider distributions.