Trees are grown from different “seeds” as starting configurations. Over the tree, a simulated “sun” travels periodically from left to right, as a moving source of positive energy spots.

Major growth of branches occurs following directions where flow of incoming energy spots is more intensive.  The figure illustrates how changes in rules and “seeds” cause notorious alterations in “adult” trees. Samples in pictures A and B share the same rule, with different initial configurations. Significant variation in branches is observed, while general structure and morphology are the same for both trees.

Pictures A and C display quite substantial differences in structure and morphology. Those trees are modeled from the same “seed” using different rules.

Picture D shows part of modelling interface, revealing the tree growth process. Bursts of energy are observed on tree nodes, where most active cell transitions take place. Across the top of the picture can be noticed the traces of positive energy spots, as they are released by the moving energy source.