http://cbr.sh/pt2y1x or https://gum.co/qHUm
This one was fun to do. At first I did the branch LOD but had no clue on how to use them "simply". Then I decided to give an ID to each LODs polys (and a specific smoothing groups, just in case) then I merge them altogether, made the bushes. Next I duplicated them 3 times (3 LOD) and then deleted the unecessary meshes by selecting their ID, and voilà. The meshes are double sided, I don't like that because it increases the polycount but I set a different smoothing group to each side to make it easier to remove if necessary.