Reproductive and vegetative bud differentiation in Olea europaea L.

The apical meristem of cv. Nocellara Etnea buds is described in the course of its anatomical progression, from July until bud break, the following spr ing. Differences in the apex of potentially vegetative and flower buds are already visible in the summer. In leaf buds the apex is a round dome, with two buttresses determined by leaf primordia. The cells of the outer layers are arranged in concentric rings, distinguished by different conditions of the nucleic acids. In flower buds the apical dome is less prominent, and th e outer cell layers are histologically quite uniform. These characteristics remain unchanged in flower buds, and are little modified in leaf buds, unt il December; in January Rower bud differentiation becomes more active, and both bud types start developing with increasing intensity. Our observations postulate a very early anatomical separation of the two bud types, on whic h further environmental factors might determine the final differentiation p rocess.