The textures for the branches are unfortunately made the same way I did the weapon models. I took a pre-made texture, chopped it into triangles or low count poly's and then positioned their visual stem to 0,0 on my leaf node manager (for the script). There is no 2d-point rhyme or reason beside that, so retexturing the leaves may take some time unless you specifically uvmap them from scratch to a new texture.
I personally use various different lighting and environment mapping techniques to make the texures look super bright or not as bright in-game. Having lived in mountainous regions before, the ones you see in the three pics above are as close to what we saw with the human eye without also tinting everything blue (which I always hated). I know in the eastern US they don't appear as brightly lit. They definitely look wrong with the vanilla NWN environment settings from the toolset. The image of the poplar branch is actually a real picture. The maple I think is somebody's hand-painted art, though I have no idea who. And the olive leaf is an image of a previously rendered 3d model, so it is more unnaturally glossy and middle textured.
If you zoom in on the texture in-game, they have quite a bit more detail, except the olive branch. The images are each 512 square I think (as tga), so there is a lot of room to play with. Definitely feel free to play with different textures, and if you care to, send me some textures to add to my tree library, which I need to basically redo because of all the stuff I lost when I switched computers.
I plan on taking a bunch of stuff for pine-family trees and building pre-rendered branches and then converting them to usable textures. We'll see how that goes
