Development of the embryo and ruminate endosperm in an early-divergent angiosperm, <i>Asimina triloba</i> (Annonaceae)

Our study provides a comprehensive overview of the stages from fertilization and early embryogenesis to seed germination of A. triloba. The results reveal both ancestral features, such as a slow embryogenesis and an underdeveloped embryo in the mature seed, and derived features, such as the presence of a ruminate endosperm, which is commonly found in the family Annonaceae. This combination of traits is also observed in other angiosperm families, suggesting a convergent evolutionary solution with adaptive significance, where a ruminate endosperm may evolve in response to specific environmental conditions. These findings contribute to a better understanding of both the diversity of embryological characters and their evolutionary significance across early-divergent and more derived angiosperm lineages.