That's a great start.  Nice work!

Now, I challenge you to take it to the next level.

With spring nigh upon us, go out and look at some real deciduous trees, before they really leaf out.  Study them.  Look at what makes them look really real versus what makes a fake fractal tree look computer generated.  The trunks and branches aren't straight; they curve and twist.  Most trees don't fork with equal strength on both sides, they send out larger branches from which many smaller branches eminate.  I'm sure that in an hour on a late winter day looking at trees in your area, you can come up with a dozen great ideas for improving your code.