Trees, and bushes, seem to make a crotch at varying lengths. This picture shows us varying length branches but they all seem to be close to a similar length: http://en.wikipedia.org/wiki/File:White_Branches.jpg. Also, some branching among trees seems quite a lot different such as this tree: http://en.wikipedia.org/wiki/File:Strom_roka_borovica_velke_borove_03.jpg.

When does a tree "decide" to make a branch? What mechanism decides the length of the branch before it forms a new branch? Why are branches roughly the same length "per generation" where older branches seem about the same length, newer branches seem about the same length, and very young branches appear as the same length?

What is the branching process called? Is there anything seasonal that causes branching or more branching?