3D Cafe
http://www.3dcafe.com/index.php?option=com_content&task=view&id=14&Itemid=80
CadPlants
http://www.cadplants.com/
3D XTRAS
http://www.3dxtras.com/3dxtras-free-3d-models-list.asp
Plants 3D models from 3DXTRAS
http://www.3dxtras.com/3dxtras-free-3d-models-details.asp?prodid=2135
http://www.3dxtras.com/3dxtras-free-3d-models-details.asp?prodid=10212
http://www.3dxtras.com/3dxtras-free-3d-models-details.asp?prodid=7689
http://www.3dxtras.com/3dxtras-free-3d-models-details.asp?prodid=9666
http://www.3dxtras.com/3dxtras-free-3d-models-details.asp?prodid=10198