L-systems have been shown to be a useful tool for modeling plants; however, the generation of realistic plant models requires an extensive knowledge of L-systems. People who are not L-system experts require a simpler way of creating plant models. This paper will describe my attempts at designing a user interface which allows the user to guide the evolution of plant models (generated from a parametric L-system) and the genetic algorithm employed to facilitate this evolution. The nal goal of this research would be a design environment in which plant models could be easily and quickly generated without explicit knowledge of L-systems. The plant models would still be L-systems but the user would not ever need to see them. By exploring the concept of evolution as a method for developing plant models we may also gain insight into the development of plants themselves.