The Effects of Sycophaga Sycomori L. On the Structure and Development of the Synconia in Ficus Sycomorus L. *

SUMMARY The anatomy of the syconia and flowers in the sycomore fig (Fiats sycomorus) has been studied. The developmental course of the ovules and pollen grains and their ultimate structure were found to be normal. No difference was detected between short‐ and long‐styled flowers. In the Mediterranean area, Sycophaga sycomori is the principal sycophilous wasp developing within the ovaries of the sycomore. The wasp inserts its egg into the embryo sac via the style. Inhabited but unfertilized syconia which do not contain plant embryos persist on the tree and continue to develop, while the unoccupied syconia drop within a few days. Inhabitation by the wasp has a decisive effect on the subsequent development of the syconia and flowers. Oviposition induces sclerification of the pericarp and proliferation of the nucellus, which serves as‘feeding’ tissue for the insect larva. Inhabitation by Sycophaga is indispensable for the maturation of the male flowers. Uninucleate pollen grains were the final stage attained in uninhabited syconia.