Context: Modelling annual shoot development processes is a key step towards functional-structural modelling of trees. Various patterns of meristem activity can be distinguished in tree shoots, with active periods of phytomer production followed by rest periods. This approach has seldom been integrated in functional-structural tree models. Aims: This paper presents theoretical research work on modelling and computation of the dynamics of tree annual shoots using stochastic processes with various development patterns: continuous or rhythmic, monocyclic or polycyclic, "seasonal" or "a-seasonal", with preformation or neoformation produced from meristem functioning. Methods : The renewal theory is used to compute stochastic aspects of phytomer production, resulting from meristem extension or rest periods and meristem mortality. Results: Continuous development can be modelled with a Bernoulli process, while rhythmic development is modelled by alternation between extension and rest periods, the duration of each period following specific distributions. Conclusion: The application of such stochastic modelling is the estimation of organ production during tree development as a component of the demand in functional-architectural tree models, used for computing biomass production and partitioning