You will use this balloon as a stem by attaching it to the flower-shaped tree top.
I used green, but truffula tree bark is meant to be fun, so make it any color you want
Blow this balloon up to only about 1 & 1/2 ft long. Tie it off. Tie off the other side of the balloon as well
Use the long empty part of the balloon to attach it to the tree-top
Twist it around and around the center of the flower-shaped top
Twist one end around the center of the truffula tree top. Winding it in and out a few times to really secure it in place
Wrap the other side around the hat base looping it around and twisting it to close the circle up and around the base.
Now, you should have a truffula tree attached to a hat balloon base