I'm wanting to make my son's birthday cake (jungle theme) I want to make palm trees. I made some leaves out of gumpaste, but they won't stick to the pretzel rods. Is there something else I can use besides gumpaste or fondant? And how do I get them to stick?

Once they dry stick them on with royal icing they won't go anywhere. Hope this helps you.

Royal icing does work well, but for a much quicker setting medium, you can use candy melts.

I agree, use candy melts to attach your leaves onto whatever you're using for trunks. That method works really well.

I just use a glob of softened fondant... Make a ball, stick in lightly dampened tips of the gumpaste/fondant palm fronds, smoosh it 'til it holds securely.