Ever notice those greenish-gray-yellow spots on your tree branch, fence post or park bench? To some, it may look like a simple moss or mold and not worthy of a second glance. But if you did look closer, you'd realize it was something quite different and uniquely beautiful. Sort of like a big brooch or gaudy piece of jewelry, adorning that tree. You would see a lichen:
So what are lichens anyway? Lichens are composite organisms formed from a fungus and an alga. Together, the fungus and alga create a symbiotic relationship, living together as one organism, both inhabiting the same body.
According to The Backyard Nature Website, the fungus benefits from the algae because fungi, having no chlorophyll, can't photosynthesize their own food. A lichen's fungal part is thus "fed" by its photosynthesizing algal part. The algae benefit from the association because the fungus is better able to find, soak up, and retain water and nutrients than the algae. Also, the fungus gives the resulting lichen shape, and provides the reproductive structures.
Pretty amazing stuff for something that most people may not even notice, huh?
Personally, I love finding these. I think they look like pressed flowers against the wood or rock. Looking closely, you can see the intricate shapes, the bumps and ridges that almost resemble flower petals or fine lacework. Look for them next time you are out for a walk.