The island of Folegandros, located between the Milos and Santorini archipelagos in the southern Kiklades (Greece), constitutes together with Ios and Sikinos the south-central part of the phytogeographical region of the Kiklades. Its flora consists of 474 taxa, 47 of which are under statutory protection, 40 are Greek endemics and 145 are reported here for the first time. We show that Folegandros has the highest percentage of Greek endemics in the phytogeographical area of the Kiklades. The known distribution of the endemic Muscari cycladicum subsp. cycladicum is expanded, being reported for the first time outside the South Aegean Volcanic Arc. The floristic cross-correlation between Folegandros and other parts of the phytogeographical region of the Kiklades by means of Sørensen’s index revealed that its phytogeographical affinities are stronger to Anafi Island than to any other part of the Kiklades.
