SpeedTree - SpeedTree is a powerful toolkit used to create 3D vegetation for video games, films, and animations.
Tree Studio - Easy 2D Tree Creation
ngPlant - ngPlant is a plant modeling software package.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Arbaro - Arbaro is an implementation of the tree generating algorithm described in Jason Weber & Joseph...
TwistedBrush Pro Studio - A powerful and unique natural media painting program.