Three aspects of the flowering process are presented and discussed: the activity changes in the shoot apex, and the role of leaves from the point of view of energy transduction and signal production. A few markers are proposed to detect the early transition from the vegetative to the floral state. Floral induction seems to be dependent on changes in membrane properties and on communication between the different parts of the plant. An hypothesis is proposed which suggests that the transformation of plasma membranes is one of the components of the basic mechanism of floral induction in the leaves.