This article is from the sci.fractals FAQ, by Michael C. Taylor and Jean-Pierre Louvet with numerous contributions by others.
A L-system or Lindenmayer system is a formal grammar for
generating strings. (That is, it is a collection of rules such as
replace X with XYX.) By recursively applying the rules of the L-system
to an initial string, a string with fractal structure can be created.
Interpreting this string as a set of graphical commands allows the
fractal to be displayed. L-systems are very useful for generating
realistic plant structures.
Some references are:
1. P. Prusinkiewicz and J. Hanan, "Lindenmayer Systems, Fractals, and
Plants", Springer-Verlag, New York, 1989.
2. P. Prusinkiewicz and A. Lindenmayer, "The Algorithmic Beauty of
Plants", Springer-Verlag, NY, 1990. ISBN 0-387-97297-8. A very
good book on L-systems, which can be used to model plants in a
very realistic fashion. The book contains many pictures.
More information can be obtained via the WWW at:
L-Systems Tutorial by David Green
Graphics Archive at the Center for the Computation and Visualization
of Geometric Structures contains various fractals created from