The process of flower bud morphogenesis of fruit trees and the general law of plant growth and development are vegetative growth before reproductive growth, that is, reproductive growth is based on vegetative growth without exception. This is true of biennial plants and perennial trees. Some deciduous fruit trees sometimes appear the phenomenon of "flowers first, leaves later" or "flowers and leaves spreading together" in annual activities, but if we regard the dormant bud of the fruit tree as a shortened branch, then the scales, leaf primordium and bract primordium attached to the branch axis can also be regarded as vegetative organs, and the primordium of flowers (or inflorescences) is based on this. In temperate and subtropical regions with four distinct seasons, the morphogenesis of flower buds of fruit trees is the rhythmic expression of the annual cycle development of trees. Mainly controlled by the heredity of tree species and varieties, it shows different fruiting habits. At the same time, it is also restricted by the development state of other organs of the tree and the external environmental conditions. As mentioned above, Luckwill once divided the whole process of flower bud morphogenesis of apple into three stages: vegetative growth stage, flower inoculation stage and flower primordium differentiation stage. Among them, the vegetative stage refers to the stage when the apical meristem produces Ye Yuan radicals (including scales, leaves and bracts), the flowering stage refers to the stage when the apical meristem changes, and the flower primordium differentiation stage refers to the stage of flower morphological differentiation. Bernier( 1970a) and Bambu et al. (1982) both think that the first stage is the period when vegetative apical tissues receive differentiation signals or flowering stimuli, but such signals or stimuli have not been clarified so far. In the flowering stage, Bambu and others emphasized that the changes of cytochemistry and tissue structure occurred simultaneously at the growing point. To sum up, the whole process of flower bud morphogenesis of fruit trees is as follows: with the growth of branches slowing down or stopping, the accumulation of various nutrients gradually increases, and the endogenous hormones in organs change, resulting in a new balance; Once this balance reaches a certain critical point, flower-forming genes will be activated, and then the contents of DNA and RNA will increase, and the proportion will change, which will promote the synthesis of specific protein (including enzymes) and cause the change of apical metabolic direction. Then the growth point began to change and differentiate in the tissue structure (this process continued until the end of flowering), and then the meristem of the flower (or inflorescence) appeared, and the primordium of each part of the flower organ began to differentiate. At this time, the reproductive tip and the nutritional tip can be gradually distinguished from each other in appearance. Although there are various theories and theories about flower bud differentiation, they probably only reflect different aspects of various substances and tissue changes in the process of flower bud morphogenesis under certain conditions, at different times and on different occasions.