Significance of epidermal fusion and intercalary growth for angiosperm evolution

The ancestral angiosperm flower probably had many separate elements in each floral whorl (sepals, petals, stamens and carpels). Derived character states include 'fusion' of elements within a whorl (cohesion) and fusion between whorls (adhesion), as well as epigyny and the emergence of the other floral elements from the apex of the fused carpels, This article considers the roles of epidermal fusion and intercalary growth in the phylogeny and ontogeny of fused floral elements, and the importance of fusion for angiosperm evolution.