Steps to repro:

1. Open Unity;
2. Create new project;
3. Extract attached package;
4. In the Project Browser go to Assets -> Scenes;
5. Open '3_Gameplay' scene;
6. Launch the scene.

Actual result:
White dot artifacts are rendered on SpeedTree leaves (see attached actual.png screenshot).

Expected result:
Tree lighting should be consistent for all SpeedTree LOD levels.

Notes:
- Reproducible in 5.5.0b7, 5.4.1f1, 5.3.6p6;
- Reproducible on both OSX 10.11.6 and Windows 10;
- Reproduces only for lower LOD levels, doesn't repro for LOD0 (mesh with higher detail);
- Also reproducible in Standalone build;
- The issue is related to Directional light that affects SpeedTree from below - even though it 's situated under the opaque surface some light still affects parts of the tree on lower LODs; if Directional light is off the issue doesn't reproduce.