As a corollary to my previous post on trees and shrubs, I'd like to point you to the parametric Onyx Tree Generator - recommended here at the GSD. Find it in public\software\winapps\Onyx\Onyx Garden 2.0. Accurate, customizeable models of various species in their ready-made tree library are exportable as 3D geometry or 2D cards to be rendered in your 3D app.
