Asynchronous flowering is widespread in plants. But little attention has been paid to the modeling of the time-course of flowering of a single plant or a population. Yet the reproductive success of many species, some of agricultural importance, relies on the overlapping of the flowering of compatible genotypes. To address this question, we present a general flowering model which integrates the flowering variability between and within trees. Following three hypotheses, three simpler models of general use are derived: the "shoot", the "tree", and the "population" models. Their behaviors are explored using simulation. The "shoot" and the "tree" models are able to simulate the different flowering patterns observed in plants.