I first heard of this from the remarkable gardens of Peter Cooke, which can be seen at their website: <a href="http://www.pooktre.com/" rel="nofollow">http://www.pooktre.com/</a><p>And it also reminds me of the fantastic sci-fi novel by Leo Frankowski, Copernick's Rebellion in which the hero genetically engineers trees to provide housing & food for the globe.