This paper can be split into two parts corresponding to two different ways to determine a functional model of growth. Firstly, the process of growth on which the computer simulation is based will be described. Secondly the theoretical formulation presented in an earlier communication will be presented. These two approaches are complementary. The simulation with AMAPpara allows the management of resources to be investigated during the growth for complex architectures, using the botanical knowledge already exploited in the first software AMAP. With the theoretical model, it is possible to analyse the behaviour of simple architectures during growth and for an infinite time. Moreover, this analytical formula is a good way to validate the results of the simulation program and to qualify its functioning parameters. For some architectural models, the theoretical formula supplies approximated results, however we will show that the resulting error is not significant. The first and more complex architecture which has been simulated with AMAPpara will be presented. The influence of the environmental parameters on this tree growth will be shown