This chapter presents the stochastic simulation of plant growth and development with GreenLab, addressing the challenges of controlling variability in stochastic plant simulations and verifying the validity of these simulations. It includes the growth of temperate and tropical trees with synchronous and asynchronous development. It introduces a method for simplifying complex plant topologies into crowns and organic series based on physiological age and common pool concepts, enabling more accurate parameter estimation through data assimilation and the inverse method. This chapter emphasizes the potential structure as a crucial tool for validating simulation results and for establishing effective inverse methods to compute sink-source parameters from organic series. It is applicable to a wide range of architectural models in botany and agronomy. The Gloups software is used to simulate and visualize plant structures, demonstrating the breakdown of plant structures into axis categories and the creation of organic series. This validation is crucial for the development of inverse methods and for assessing the GreenLab model’s accuracy with natural plants.