Commenting post 142:
I have all that stuff here too, fortunately!
the blender greenhouse (blender trees with textures included): http://yorik.uncreated.net/greenhouse.html
the rendered textures: http://yorik.uncreated.net/archive/textures/index.html
the ngp files + textures used to create them: http://yorik.uncreated.net/archive/ngplants/
the povray plugin I use to render the images directly from ngplant: http://yorik.uncreated.net/scripts/ngplant-povray.html
Feel free to use anything you might find useful. But note that these trees are not exactly suited for games. The 3D versions are way too heavy for games, and the textures are flat renders, made for billboards, which are good for animation but not too good for games. One solution I used already is to use them for vegetation that is far from the camera. Then, using the textures and doing a "cross" with 2, 3 or 4 planes works well, like this:
blend file here