Recent developments in theory and technology in performance based design show an interest towards generative systems. In this paper a morphogenetic approach will be introduced that looks at Goethean morphology and leaf venation patterns. To instrumentalize this approach an algorithm will be introduced to generate various leaf venation patterns on complex mesh surfaces. As a case study, the paper tests the applicability of such system as performative algorithms for building envelopes. The role of simulation is to generate self-organizing forms and provide a framework for design development. The overall approach is to consider performance as a direct input to guide the computation of form at an early design stage.