Abstract : We describe a complete lighting simulation system tailored for the difficult case of vegetation scenes. Our algorithm is based on hierarchical instantiation for radiosity and precise phase function modeling. It allows efficient calculations both in terms of computation and memory resources. We provide an in-depth description and study of the instantiation-based radiosity technique and we address the problems related to generating and managing phase functions of plant structures, as needed by the instantiation process. We present results demonstrating the high performance of the hierarchical instantiation algorithm and we describe two examples of applications: rendering of large vegetation scenes and plant growth simulation. Other applications of our system range from landscape simulation to agronomical and agricultural studies, and to the design of virtual plants responding to their environment.