In the capitulum of sunflower the process of generation of new floret primordia starts at the receptacle rim and continues towards its center. Then, each floret primordium differentiates gradually over space and time, in the centripetal direction. The florets appear in an annular generative zone first as a gentle dome and then become a two-part structure: the floret bract and the floret corolla.

This paper provides a detailed description of the beginning of the floret primordium differentiation during the floral morphogenetic process in the sunflower capitulum.