I've posted on making different types of pine trees using dowels with furnace filters as needle supports and wire branches with static grass for needles. Decidious trees I've made with twigs and poly fiber and or furnace filter material covered with the super leaves. For me the wire arbor is the way to go. I think the fiber gets too dense. But could be ok for deep background trees/forest. Essentially puff ball trees.
If you have any dried sedum around, those could be glued together to form a 4 or 5 inch tall tree without too much trouble. I could not get hydrangea heads to work.
Luke Towand has a nice video on making wire trees for ho scale. He uses fiber static grass ground foam and leaves for the leaves. There is a product called seafoam a plant which could look good with some fiddling. I do not like the adhesive spray, it sticks well, but dries slow and will collapse the structure if if you compress it at all.
