Above is my attempt at creating the famous Barnsley fern [1]. It is one of the better known examples of a self-similar set, the other key example is the Sierpinski gasket.
The Barnsley fern resembles real species of Asplenium ferns, see below.
References
[1] Michael Barnsley, Fractals Everywhere, Boston, MA: Academic Press, 1993
Links
Wikipedia entry on the Barnsley Fern