A choice perch

What's that green stuff hanging from this tree – part of its foliage? No. It's actually lichens (Living organism resulting from the symbiotic union of a fungus with an alga or Cyanophyta.), using the tree as a substrate. Plants that grow on other plants like this, without harming their hosts, are called epiphytes (Organism living on another one without parasiting it.). Although the lichen benefits from the arrangement, the tree really couldn't care less! This type of relationship is called commensalism.

Many different organisms make their homes in trees. Their trunks and branches are virgin territory just waiting to be colonized. According to some estimates, trees and shrubs worldwide act as hosts for nearly 34,000 species of epiphytes!