This text summarizes the results of studies on the pollination ecology of the unique family Compositae (Asteraceae). The complex structural and functional specializations of the capitulum (or head) for pollinator attraction and pollen transfer are described in detail. An attempt is made to identify the influence of these specializations on the development and the function of other floral parts. The remarkable sex polymorphism of the Compositae head, which has caused much confusion amongst students is traced to this influence and characterized as a secondary modification. The central concept in the book is taht pollination ecology is the guiding factor in Compositae evolution.