That's not really saying much, haha.
Palm trees you could actually pull off OK with some custom textures. You'd need an appropriate bark texture and some palm fronds textures with an alpha channel. You could then set the trans33+trans66+mist flags on the frond brushes. and make it look pretty convincing. It would be kind of tedious to do, though, and would probably look better modeled.
The rest of the map looks nice, though -- just needs a few texture alignment tweaks on some of the stones.