The simulation of branching patterns in modular organisms

A modular mode of growth in an organism is frequently coupled to the development of a branched structure. Such modular forms may appear to be constructed in a regular manner, exhibiting a high degree of organization, or may be bewilderingly complex and yet not haphazard. These factors, together with the very nature of systems dependent upon the progressive addition of modules, readily promote attempts to model branching processes by means of some sort of constructional simulation. Such models tend to favour visual, graphic presentation. This paper considers aspects of modularity and branching and the different approaches to the modelling of branching organisms, and gives a range of examples. Attention is directed towards the aims of the models and to their different characteristics rather than to a description of the computorial methodology involved. Attempts to simulate branching systems highlight the constructional similarities and differences between various modular organisms, but one key factor is identified for both real and artificial branching patterns: it is the nature of the control of new branch initiation that governs their constructional development.