Taking a Likin’ to Lichen

Sure there are loads of people who love to admire all sorts of animals, plants and rocks and minerals and things of that nature and that is fantastic, but how many people do you know who stop to observe the smaller organisms such as fungi, lichen and moss? I sure don’t know but one or two people! The specific organism of today’s post is lichen. So just what is lichen? Well it’s a lot more than just some green stuff on rocks and trees! Lichen is actually an organism made of other organisms that could for the most part survive on their own but living in such a symbiotic relationship has proven successful in gaining nutrients. Lichen is made fungi, the mycobiont, and any species or combination of species of the prokaryotic Cyanobacteria (blue-green algae), or the eukaryotic Chlorophyta (green algae) and Xanthophyta (yellow-green algae), called the photobionts. Blue-green algae is less common and occurs in only 8% of all known lichens. Some lichens are similar to extremophiles (organisms that live in extreme environments) in the sense that they can live in deserts, tundra and rocky cliffs, but lichen is also widespread and common as a epiphyte on rocks and trees. Epiphytes are organisms that live on, but are usually not nutritionally harmful to other plants or objects. That is, most lichens gather their food sources from elsewhere. Spanish Moss is an example of an epiphyte as well. What is so cool about lichen is that two different organisms can come together to help each other live as one! The fungus typically surrounds the algae and its role is to retain water and nutrients and to protect the algae.    This is why lichen can survive periods of severe droughts. In some cases where the lichen is parasitic, the fungus provides the minerals from the plant off which the lichen is growing. The green algae and cyanobacteria play the role of gaining sugars through photosynthesis. In some cases where a fungus lives with both green and blue-green algae, the cyanobacteria can change nitrogen gas from the air into ammonia to complement the green algae’s role. Both organisms also work to draw water and minerals out of the air and from rain and dust. So aside from being scientifically interesting, algae does take on many cool colors and shapes and can even aid some wildlife like Northern Parulas! There are predicted to be over 1500 species in Georgia alone, and many cannot be identified without a microsope, but for those Georgia residents, here are two links to guides to common, conspicuous species of lichen:
Even though the behaviors of animals are what draw so many people to watch them, start paying more attention to these ornate teammates because you might find them pretty cool!

Old Man’s Beard
Texas Shield Lichen