We saw Tom Stoppard's Arcadia last night. I don't need to tell you that it's a wonderfully mind-bending couple of hour that touches on literary authenticity, 18th trends in gardening, the second law of thermodynamics, Lord Byron and his devilish ways, the heat death of the universe, iterated equations and much else besides.
Iterated equations? Yes. Feed X into equation, get Y. Let Y be the next X and repeat. From such humble beginnings can come all the patterns of nature. For instance, take a look at these truly extraordinary computer generated flowers: