The following model shows that this instruction leads to a simple inflorescence with seven ramifications after seven successive steps. 0. As a result could the units decrease with each step, or a shape with small bottom and top and larger middle units could develop. Such modulating factors may be hormones whose spreading through tissues can be explained by gradients. Switches represent active or inactive genes whose activities are required for the development of the structure in question. In this way can they activate numerous further genes at a lower hierarchical level, like a set of genes required for the development of a flower or a leaf.
Homeotic genes are thus on a high hierarchical level.
Their switch function determines the generation of specific morphological structures. Acripetal and Basipetal Spreading of a Signal. In the first case develop flowers and fruits from the bottom of the inflorescence first, in the second case occurs differentiation from the tip to the basis.