Very Nice final.
I should have said that when a variation color (like a red orange for example) is used, I find that most often the diffuse color setting in the default shader of the leaf image has to be set to full white, 1.0 or even beyond full white like 1.5 or more. It probably depends on the darkness/tint/saturation of the leaf image file itself. Xfrog images usually seem to need a lot of boost. Dueling tints in some cases.