Meetings of the Royal Botanical Society of The Netherlands

Although the Annonaceae are a large family (c. 120 genera) they are remarkably homogeneous in their morphology. The basic concept of an Annonaceous flower consists of one whorl of 3 sepals, two whorls of 3 petals each, numerous stamens, and many carpels. Genera are delimited by usually small differences in the number, size and/or shape of each of these parts of the flower. Generally the flowers are pollinated by beetles. An extensive study on the morphology of the flowers, on genus-level, revealed several morphological trends, as well as the importance of the aestivation for the morphology of the flower. The two main aestivation-types in the Annonaceae are the imbricate and the valvate aestivation. Especially when the petals are valvate, there is much variation in the morphology of the flower.