This project, written in Processing, creates a fractal tree.
The idea is to so what kind of asymmetries are needed to create a realistic looking tree.
The tree is created recursively: each branch functions as the trunk for a new tree.
The line segments in the gui can be dragged by their end points to change both the ratio of the left and right branches and the angle between the branches.
The two tree icon buttons can be used to select alternating branches (the ratio of left to right branch lengths alternates) or non alternating branches.
I've experimented a little with different gui's. In particular I thought it would be nice if the branch length/angle control segments were actually the trunk and first two branches of the tree. I wasn't happy with my initial attempts, but would like to revisit that idea.