They look like Bonzai trees.
You need to rework the proportions of the trunk and make
more realistic leaves. (not every leaf single, but rather
"bulbs" of leafs), the leafs must be much more dense and cover much more of the tree.

I also agree that they dont look like jungle plants, but rather like (single standing, and wind-worn) mountain trees.

A jungle has dense vegetation, forcing the trees to be very high to capture any sun. Also they are often covered by moss and other secondary vegetation.