The free Xfrog plants for Artlantis are a collection of more than 100 high quality 3D plants in the Abvent Artlantis .AOF format.
It's a 700mb download, but totally worth it. One of the things that makes Artlantis so great is how easy it is to populate your scenes with entourage. This just makes it even better. Support their site and Like them on Facebook when you're there!