A second ramification can evolve only at a sufficiently large distance from the previous one. The development of rows is characterized by the attempts to maintain a distance from the margin. Such a developing network is marked by a high stability. If, for example, all differentiated cells of one of its halves are removed, then the network will regenerate. The new part would resemble the pattern of the original one but not be alike.
Most ramifications end blind and backward connections are rare - both in the model and in nature.
A decrease of S along an existing row has the weaker effect so that a growing and an existing row repel each other far less than two rows that grow towards each other. It would then produce dichotomous ramifications and backward connections would be impossible. As a consequence are the developing structures mechanically unstable. Dichotomous ramifications of leaf veins developed earlier during evolution than complex networks. They occur, for example, among pteridophytes and gymnosperms while complex networks are typical for angiosperms.