I play with recursivity and randomness.
BTW,is this really evolution?
You should create some competing standard like like surface area when crowded or unlikelyness to get ate by squirrels
The great thing about randomness in trees is that it's a great exercise for students to work out how not to get lost on the way back down!
But my friend and colleague Paul Goldenberg likes to point out that you can get much more realistic and interesting trees than the one on the left, which is typical of the textbook tree because things are spread out enough to make it easy to circle the left and right branches, without randomness by using smaller angles, multiple branches, and branches at various heights up the trunk.
I don't believe it is really evolution unless there is a factor to determine what genes live or die.
You could make it artificial selection, picking random genes from the start, and randomly adding adjustments, the player could then choose whether or not they like this new tree, and keep it, so it may mutate more and repeat the process, or discard it, and keep the last tree, mutating until the player is happy with it.