Attached Link: http://www.inf.tu-dresden.de/ST2/cg/downloads/publicplants/

Hi Dan, if you want plants in .3ds or .obj format, you should think about getting Xfrog. It is a special modelling program for vegetation - you will be able to make flowers as well as trees and other organic forms. Allthought it seems to be very complicated it isn't - and after some practice you'll even be able to animate your plants, let them grow, or let the wind play with the leaves. I am not that far yet, but i think you get the best vegetation models with Xfrog. I'll attach a picture made by Xfrog-stuff with some foliage and a link to their free models. If you got questions regarding Xfrog i'll gladly try to answer them if i can. Lutz