COMPARATIVE STRUCTURE OF OVULES AND SEEDS IN RAFFLESIACEAE

The genera of the Rafflesiaceae show a marked diversity in the structure of their ovules and seeds. Evolutionary trends are recognizable in ovule orientation and number of integuments. A change from anatropous ovules in Apodantheae and Mitrastemoideae towards incomplete anatropy in Rafflesieae and orthotropy in Cytineae occurs, next to a change from bitegmic ovules in Apodantheae towards unitegmy with rudimentary outer integuments in Rafflesieae and Cytineae and full unitegmy in Mitrastemoiceae. -The differences in ovule structure are clearly reflected in the seeds. The seeds are essentially exotegmic, have very small embryos and an oily endosperm. -Seed structure strongly confirms the existing subfamilial classification and supports additional arguments for the generic status of Apodanthes. It does not support a separate status of the genus Berlinianche. In Rafflesiaceae, seed micromorphology is only of limited use at the species level. As far as known seed dispersal is endo- or exozoochorous in all genera.