Since the publication of the tenth (supplementary) volume of the Flora of Turkey and the East Aegean Islands, twelve years have passed. Within this period of time, the interest of both foreign and Turkish botanists in the flora of Turkey has not diminished but rather gained momentum. In the last twelve years more than 400 new flowering plant species, either new to science or new records, have been described or recorded from the area of the Flora. In addition, much new information about the richness and interest of the Turkish flora and its importance as a centre of diversity has come to light. All this new knowledge has necessitated the preparation of a new supplementary volume to Professor Davis's monumental work.