Looks nice! That yellow-green-ish color on the trunk is a little out of place and the small branch (that goes to the right) seems to have leaves where it shouldn't (if just those 5 pixels would have been brown, it would've looked better).
But hey! I'm in no place to tell you what to do! It looks great!
looks pretty good to me! I think you probably don't need that transparent pixel in the upper right leaves, and I think your branch that goes to the right looks like it thins out too fast, add a bit more bulk to it and surrounding leaves.
For lighting, the trunk almost looks as if its backlit, might want to play with that, I think even with where the leaves lightsource is, you could get a bit more light on the trunk.
Its a good shape if you are going to use for gaming, and want to limit transparency and collision issues. But if its just for fun, I say you could try and get a bit away from the lollipop shape, branches midway up the tree could be nice, or low hanging leaf clusters, maybe a hole in the trunk where a branch used to be
Cool. Thanks!