You can use power fractal shaders to adjust the colours in many ways.
If you wanted the leaves to be green, but retain some of the UV texture data, you can load the texture as a Image Map Shader, than use the Convert Colour to Grayscale. From here, you can use a Add Colour shader and a PF to add new colour definition to the grayscale image map.
I'll post an example in a moment. I just realize I have no vegetation objects (again) due to various issues I had migrating to a new PC with a Seagate 2tb (Don't trust Seagate with valuable data, seriously)