I learned about L-systems the other day, so here's my first shot at making one. It generates a plant whenever you hit the main action button.
L-System Parameters:
Constants are any characters that don't appear as a rule index - all rules for a given variable have an equal chance of being chosen. The generator runs five iterations for each plant.
A means "go forward," B and C mean "turn and go forward," {} and () mean "start a new branch and turn afterward," and . means "draw a circle."
All animation comes from the rendering portion - the L-system only runs to initially create the plant.