Replies

That's a good post on the fractal geometry of trees. But here's the next question: how is this information encoded in DNA and how does the tree use the DNA information to grow using this fractal design? This is where it gets very tricky scientifically. I took a good class in molecular biology and these are not simple processes by which information in DNA is utilized.

"But here's the next question: how is this information encoded in DNA and how does the tree use the DNA information to grow using this fractal design?"

Branching(budding) and growth is generally regulated by exposure to sunlight and nutrient production. The tree has an inherent growth capacity and total nutrient requirement for it's size. The tree can sense which direction to grow by the amount of nutrients produced in a certain branch. If the cambium is exposed to sunlight budding happens and a branch forms. All branching is effected by mechanical forces and the branch grows to reduce stress. The same goes for the roots, but there the drive is for water uptake.

The tree fractal pattern is just the simplest and most efficient way to accomplish the above farmer's version of tree growth. The tree starts with the first 2 branches from the 2 halves of the seed. The fractal image of the tree looks similar from the time it's small to when it's at full growth. The DNA doesn't contain instructions like the computer program that says grow branch one, then branch after those branches grow a fraction of branch one's length, then branch again after a fraction of that length... It contains the bluprint for the hormones, like auxin) and other growth regulators that allow increased growth in the areas where sunlight is available. It contains info for the regulator that determines total budding.

Here'a the fractal link.

There's some animations there that show the tree at various levels of branching. Real trees effectively, don't go beyond the first few levels of branching. In real trees, branches that don't produce are shut off and die. From what I've seen of real trees, including pines, most branching arises out of annual buds. Otherwise it's to reach out and grab sunlight, because of competition with other trees, or trimming(nutrient driven).