We have just released the Beta-test version of a new, free, add-on application for SketchUp - RpTreeMaker.
RpTreeMaker generates fractal trees based on parameters - tree type, number of trunks, number of roots, age, bending parameters, etc. - and the creates a tree image and places the tree as a 2D, always-face-camera, component into SketchUp.
Here is a sample Tree Image:
Here is a sample tree loaded into SketchUp on the 3D Warehouse:
Here is some documentation on how to use it:
Go here to download a copy:
Give it a try and let us know what you think.
Remember this is still in Beta Test - we plan to make improvements based on your comments. One feature still to be completed is to provide a polygon background for the tree so it will cast a shadow. For now, you can use the FormFonts script: ImageProfileto generate a polygon from the image to cast shadows.