by Barry Davies BEM. When we think of jungles, we often think of a densely forested area with thick foliage; this is what is known as a primary jungle. But jungles can also include swamps, grasslands, and cultivated areas. Primary jungles can fall into the category of either a tropical rain forest or a deciduous forest, depending on the types of trees and plants found growing there. A tropical rain forest is typified by having tall trees whose upper branches interlock to form canopies. Yet of all the environments in which man has to survive, the jungle offers the best chance.