XVI International Botanical Congess
The developmental and evolutionary enigma of variation in endosperm development (cellular, helobial, nuclear) has long intrigued botanists. Here, phylogenetic methods (using recent molecular phylogenies of angiosperms) are used to examine evolutionary patterns of change. These analyses suggest that the ancestral angiosperm had cellular endosperm, helobial endosperm is not an evolutionary intermediate between the other two, early angiosperm lineages retained cellular development, but there is a trend of shifts away from cellular and toward nuclear and helobial endosperm in large clades (monocots and asterids I-IV), this shift occurred early in the evolution of rosids I-II which shows a uniform pattern of nuclear development.