does anybody know how to make a jungle tree or any idea on any tree

Do you want the cake to be a tree or do you want a "jungle tree" as an accent?

i want it to be an accent on the top of the cake

Try modeling chocolate.

How about Rice Krispies treats covered in modeling chocolate?

I made a tree on a "jungle" baby shower cake. I used a large pretzel stick for the trunk, then made leaves & coconuts from fondant. You will need to let the leaves dry then attach them to the tree with gumpaste glue and hold it for awhile. I will try to attach the photo if I can find it.

Check out my second fondant cake... Although you can't see it very well, it does look like a real tree in close up. What I did is I wrapped the pole with fondant (in this case you use RKT wrapped in fondant). You can just shape your fondant whatever you want to make the roots and the texture it without worrying about the imperfections. I then drizzled it with melted chocolate and paint the missed parts with chocolate.

I have numerous trees on cakes in my pics. The giant pretzel ones with royal icing piped on with a leaf tip are easy. They're kind of tall and skinny, but I like that look. You can add a second layer of royal icing after the first is dried to make them a little fatter. I actually moisten a dowel and slowly work it into the pretzel from the bottom and leave about 3" of dowel sticking out the bottom so I can secure it into the cake. I'm always afraid that if I just stick the pretzel into the cake it'll get soggy and soft and fall over. It might not, but I don't want to risk it.

I've also done gumpaste molded around a dowel with gumpaste palm fronds on top. If you dry the fronds on a 2 liter bottle of pop it gives them a good curve.

Good luck!