PLANTS - Uncovering Da Vinci's rule of the trees

"all the branches of a tree at every stage of its height when put together are equal in thickness to the trunk."if a tree’s branches were folded upward and squeezed together, the tree would look like one big trunk with the same thickness from top to bottom.Trees are fractal in nature, meaning that patterns created by the large structures, such as the main branches, repeat themselves in smaller structures, such as smaller branches. Each new branch takes after its "mother" branch, mimicking the fractal nature of real trees.the diameters for each branch that limited the chance of snapping. Accounting for every part from the smallest twig to the trunk, the simulation seemed to produce Leonardo's rule.Eloy found that the proportions in his model trees stayed the same regardless of wind speed or the height of the branches, as the rule would predict. data collected in the field has shown that trees across many species obey the rule.

http://www.physorg.com/news/2011-11-uncovering-da-vinci-trees.html