Should add a few root doodads at the base of where the tree interconnects with the cliff face (the palm), just enough so that it's just touching the water.
I'm pretty sure that plants that grow out of the cracks in rocks would have their roots sprout from them.
Vines are a different story though; Blizz vines don't look too great on solid rock even if you alter the dimensions.
Got lazy with last week's one so here's my entry. Feel free to use the terrain if you want (although it is pretty small).
Probs should've used better lighting but...meh. Forgot to add the skybox in too.
Oh, the ghosts aren't actually floating in mid-air either. The building doodads just go transparent when the cam zooms in close to them.