Plant architecture is a fundamental parameter to be used for biomechanical investigations. Complex branching organization of both aerial and below ground compartments often constitutes the missing part of the structure in such studies. Examples of applications are presented which show the interest of architectural models for the numerical analysis of tree stability, including root anchorage and the dynamic behaviour of the aerial system. It is also known that there is a strong linkage between a plant's growth and its mechanical state, therefore a model of tree biomechanics has been implemented in the software AMAPpara (CIRAD, France). This model includes the mechanical role of reaction wood in tropic movements. Some simulations of tree response to environmental constraints are presented.