Ferns are primitive plants found worldwide. Because they do not have flowers, they need water in order to reproduce. This restricts their range to relatively damp regions, so of course, rainforest is ideal! Walking through a forest in the Amazon you encounter many different kinds of ferns. Some are terrestrial, but a large number are epiphytic (see Palms). Most epiphytic ferns grow high in the canopy alongside orchids and bromeliads. Ferns are characterized by feather-shaped leaves, comprised of many leaflets and woody stems. As mentioned they lack flowers, instead producing spores from little circular structures (called 'sporangia') on the underside of the leaves. The taxonomy of tropical ferns is poorly known, and the biodiversity of this group is uncertain, although for the Amazon it is relatively high.