Hi !
If you see the textures in the CE viewport when the trees are generated, then it's an export problem.
Maybe you altered some of the export settings.
If you'e in the export window, use the default export presets at the very top of the exporter window. Depending on the actual target application, there's sometimes presets defined.
Let me know ..
Matt
ps. in kml and kmz file, the textures are stored within the file..