How do custard apple fruits form from the flowers of Annona species?

In the genus Annona, the formation of custard apple fruits begins with the process of pollination, where pollen is transferred to the receptive surfaces of the pistils within the flower. Following successful fertilization, the flower undergoes significant changes: the petals drop off, the anthers and stigma wither, and the ovary begins to enlarge.12

While the fruits of the Annonaceae family are generally classified as berries, those of the Annona genus are distinct because they are often fused together to form aggregate fruits. This process involves the maturation of the individual ovaries into a single, succulent, and often scaly structure. The primary biological purpose of this mature ovary is to protect and facilitate the dissemination of the seeds contained within.3452