Thorton W. Burgess once wrote: "There are stranger things in the world today than ever you've dreamed could be; there's beauty in some of the commonest things, if only you've eyes to see." Perhaps he was referring to lichens.
Lichens (pronounced "like-ens", not "litch-ens") are found just about anywhere you care to look for them out of doors, yet very few people truly understand the unique and important role they play in our ecosystem.
However, awareness is growing, and now there are field guides being published to assist us in identifying the crusty coatings found on rocks and trees.
In days of old, when plants and animals were first being assigned scientific names, lichens were viewed as the trash of vegetation. Despite there being many types readily found, they were all grouped at that time into one genus, Lichens. Today, in our enlightened world of ecology, we know that there are about 18,000 species of lichens found around the globe.
So what makes lichens so different from other plants? That, dear readers, is the big question. Although grouped with fungus for a while, lichens have shown that they don't act like fungus. Nor do they behave like a proper plant, nor even as a well-defined alga. Lichens are, well, kind of special.
Their structure is that of a fungus, the shape and growth of each species defined by the fungal part of the beast. Then, inside the fungus structure is found a species of algae, which keeps busy turning sunshine into energy, which the fungus uses to grow which allows the algae more room to make more energy which allows the fungus to grow, and so on. The fancy word for this relationship is 'symbiosis', a mutually beneficial relationship.
Joe Walewski, author of Lichens of the North Woods, uses the following story to teach students about lichens:
Freddy Fungus lived alone in a large home that he had built himself. Despite his building skills, he was in rough shape as he couldn't cook and was starving to death.
Nearby lived Alice Algae, a master cook who could make something out of thin air. She loved cooking and often made more than she could eat herself. She too lived alone, and was exposed to the elements.
When they first met, it was obvious they should be together, as they took a real 'liken' to each other. Freddy and Alice formed a symbiotic relationship and lived together happily thereafter.
This is a cute way of understanding the bonding of two organisms to make a third. But it doesn't end there. A third partner has recently been found within lichens, a cyanobacteria. This bacterium is excellent at extracting nitrogen from the air and securing it in an organic form. (Nitrogen, which is essential to plant growth, is not found in the soil, only in the air ... it has to be captured and stored in some manner ... which is what plants in the Pea family do very well, but that’s another story).
So, that seemingly simple growth on a rock has proven to be a very complex relationship between Freddy Fungus, Alice Algae and Cindy Cyanobacteria. Together as a team they make it all work.
Lichens are identified by first determining where they live, and then by what they look like. They grow either on rocks, trees or soil. How easy is that? And they look like either a flat crusty coating stuck firmly to the surface, a miniature tree of some sort, or are attached to the surface by a thin stalk.
The first group, the crusty ones, are called Crustose (seems to make sense). These species look like they were spray-painted right onto the rock or tree bark, such is their adhesive appearance.
The second group are called Fruticose and are characterized by their somewhat upright growth. And that leaves the Foliose lichens, which are supported on a thin stalk yet will be quite near the surface.
When you stop to recall the lichens you've encountered, the ones that stand out are probably British Soldiers, Pixie Cups, Reindeer Lichen and those circular grey patterns on the rocks. But there are so many more. Walewski's guide book has 111 species, and those are just the ones found in northern Ontario.
Once you get looking for and discovering the variety of lichens in our area, you may be amazed to find a single maple tree may have up to 20 species of lichens growing on the bark. A rock in a farm field fence could be supporting a dozen different types of lichen. There is no dearth of lichens to be found.
However, lichens have disappeared from some areas. This is due to their inability to rid pollutants from their system that have been extracted from the air. Trees can absorb carbon and poop out that useless (to them) oxygen; lichens just keep it all inside. As air pollution became more toxic and more frequent, some lichens literally choked to death on the bad air. How significant is this? Read on.
Consider that lichens can survive extreme temperatures and even excessive radiation. Lichens have been taken into space and exposed to the harshness of that environment for two weeks, only to return and continue growing without interruption. But our polluted air killed them. Now that's scary.
When you look closely at a lichen, the pattern of its growth, the variety of colour and the method of its attachment to the substrate will provide good clues as to its identity. Freddy, Alice and Cindy are combining to give us another world to discover, often as close as your backyard.