Play with the parameter to see what sort of trees you can grow. Click the green flag to run with your new settings. Lengths are a percentage of the initial line (which is 100 in length). The angles determine in which direction the tree grows.
@kieranblackley created a nice project using recursion and I decided to make it more customisable. I simplified the main block and added some color changes and leaves. I also made it so the user can change the branch angles and length to make the tree look different.