Is there a shading model for "masked vertex lit" materials?

I am making LOD’s for trees right now. For the last LOD I have an X-Shaped model with a simple texture (with alpha) applied to it. That works for me, except that the model has a weird self shadowing due to its x-shape:

89334-untitled-2.jpg

So I was wondering if there is some kind of masked shader with cheap alpha transparency and some kind of vertex lighting (like the Translucent Shader). You know, to make the model just evenly lit by the (movable) directional light without any self shadowing. Thanks in advance!

Translucent shader is looking gut, but very expensive. Is there some kind of tradeoff? Masked but with simple lighting?