Buds from 18-year-old Shahmiveh pear trees were collected intermittently between June 5 and March 10, then fixed in FAA solution. The morphological processes of differentiation and development of the flower bud were followed through Scanning Electron Microscopy (SEM). In general before June 20, the apical meristems were small with scale primordia being initiated, but on 28th of June (84 days after full bloom) twelve scales were formed with the first visible signs of flower bud differentiation being observed on July 5. At this stage, flower primordia were ovate. On 15th of July, the apical meristem swelled and thickened, with bracts and florets being initiated simultaneously in the axil. On July 30 the primordium of inflorescence was completed and the primordia of sepals were formed in each floret. On August 10, the petal and stamen were formed, and on August 30, pistil was initiated. The times of flower induction and initiation were determined to be June 28th and July 5th respectively. Therefore any practical management to optimize floral initiation should be carried out before June 20.
)