I had made the tree using add-on in Blender render. 1.But many of the leaves end aren't join to the branch (after using texture and i don't use UV) 2.Selecting all leaves in edit mode and after pressing Unwrap the Blender stops responding(maybe due to too many leaves.) Is there another way to unwrap.
The leaves generated by the Sapling addon are already unwrapped. You should be able to texture them without unwrapping.
Incidentally, you can unwrap them the same way that the addon does by choosing "reset" as the unwrap mode. This just maps each face to the whole UV area, so you can use one image for all of them.