Quote Originally Posted by waldronate View Post
http://algorithmicbotany.org/ has lots of useful information on L-systems, mostly with an eye to generating plants but that are also generally applicable.
From that site you can also download a demo version (which expires at, I believe, the end of this year) of L-studio, a (almost exhaustively) fully-featured L-system development environment. If you're going to experiment with L-systems, that's the software package I'd recommend.