I would make them in 2 inch squares
2x2 square will be the base of all the rest, others would be "L" shape, "I" shape, "T" shape "X" shape and 4x4 square.
I would use Aquarium plastic plants, HO scale Palm Trees, HO scale Bamboo plants, HO scale plastic Trees, and Brown model ship rigging line for vines and will use cheap paint brush brisles for tall grass.
The idea of jungle terrain is to make an impassable area. One could almost make a maze using this idea.
Area of gaming wold be great for Pulp Games, Modern Games, Jungle Planet Games.