... includesub-models describing the interactions between the rootsand their exogenous environment, the soil. However, the organs of the plant, especially the roots, do not interactonly with their exogenous ... within the root sys-tem, via the alteration of an endogenous environment.In the third example [19], the heterogeneity of the endogenous environment was revealed by temporal vari-ations of the ... translating the developmental events into a set of formal production rules. The major strength of these models was their ability to simulate simply the relevant topological character-istics of the root...