If you want to make some cheap disiduous (spelling?) trees-ie oaks, maples, etc., get a roll of "mechanic's wire" or bailing wire. You could also use a wire that is sold in craft stores. Cut a bunch of pieces six inches or so long, and twist them together for an inch or two. Then separate the wires into two or three or even four individual bundles. Keep twisting them together for an inch or so, then separate them again. What you are doing is making a "tree armature" out of wire. Paint the armature a dull brown/grey color. Once you have the tree armature made to your satisfaction, add some of that "stretchy green stuff" mentioned previously. Spray the tree with the cheapest hairspray you can find, and sprinkle on green ground foam. If you do the first coat of ground foam with a darker shade of green and then respray and use a light green over the top of the dark green you will get some highlights on your trees. By the way, if you want to model Florida cypress, make the individual roots off the bottom of the trunk the same way you do the upper armature, and plant them in the swamp.