A computer model, simulating geometry and development of the branch system of Tabebuia rosea DC, was constructed. Early in development there is a transition from symmetric bifurcation and exponential increase in branch number to asymmetric branching, manifest in the morphological differentiation into leaders and lateral shoots and in the progressive reduction of increase in branch numbers. This reduction is an inherent geometric property of botanical trees and similar, branched systems. It results from the discrepancy between the increase in crown surface with the second power of branch order and the exponential increase in branches supplying the surface. In symmetric branching, mother and daughter branches are arranged in the same plane; in asymmetric branching, branch planes of leaders and laterals are inclined against each other. Development was assumed to be controlled by flux distribution within the tree: (1) Flux supplied to a terminal branch determines its vigor and branching potential. (2) Asymmet...