Unfortunately I couldn't find a lot of information about it on the Internet, but in Brazil we have the world's largest Cashew ( http://en.wikipedia.org/wiki/Cashew ), which is a single tree that covers a 7500m2 area.

http://www.natal-brazil.com/portugues/entretenimentos/cajueiro-pirangi.html

Check the last picture in the page. That huge green area? That's one single tree.