Tell us how you made them great palm trees.... 
in case it's me you talking to ...
The tops are just some artificiel leaves, as You may noticed already. The stem is some small branch from a "corksrew willow" (literaly translated from German, not sure if it is just an ornamental plant of some willow subspecies, but I doubt that), wrapped around is some tape used for painting windows (and NOT letting the colour dribble on glass and frame). But not the smooth one, but a roughly textured one.
Mind to wrap it from top to base, not the other was round for having this palm-like structure. I primed it with brown and a lighter brown, then brushed it with - I think BronzedFlesh or something.
I have seen a similar technique in here with just some more or less thick cord and in result a far more distcinct stem-structure. However, I guess the tape will work much quicker - so it depends what is more important - time or speed. Also the tape will propably work just for smaller stems.
best wishes
Drachenklinge