Have you ever stopped to look closely at what seems to be a pale green forest ogre’s face looking at you from the bark of a tree? Perhaps you noticed a long stringy beard hanging from a twig nearby, or a light green ruffly arrangement on the ground with fuzzy trumpets sticking out. And if that were not enough to stop you from your wanderings, you may have, if you zoomed in, found red balls or yellow cups or black polka dots.
Most likely, you were having a close encounter with what we now call “lichenized fungi,” ancient organisms that can teach us about getting along with others and about making the best of a bad situation.
When I first started thinking about lichens, the poster children of symbiosis, I thought they might make a nice story about cooperation and partnerships — helpful themes for entering 2021. They are fungal structures that have acquired photosynthetic organisms to live with and feed them. The more, however, I learn about lichens the less equal the relationship appears — lichens are closer to human agriculture, with one species benefiting more than the other. But after some millions of years together, the partners have not divorced, and in fact once lichenized, cannot grow without each other.
Fungi are found neither in the kingdom of plants nor animals but have their own branch on the end of a line of eukaryotes, which means they, like us, have nuclei inside their cells. We have more in common with fungi than we do with plants, as no matter how clever we are, we cannot make food inside our cells from sunshine. Nor can fungi, which rely on their ability to decompose others and absorb mineral nutrients. All those little threads you see in the forest floor are fungal hyphae breaking down wood, leaves and dead animals. Fungi also are good at forming relationships with others — making deals with plants that run little green chloroplast factories creating sugars from the sun.
Whereas we harvest plants to eat, or to feed to animals, which we eat, fungi have their own sort of farming. Fungal rhizomes have joined up with tree roots, extending their reach, providing mineral nutrients and water in exchange for some sugars. These mycorrhizal mats connect entire forests and help with the exchange of energy throughout.
In the case of lichens, a fungus once captured an algal cell and wrapped its hyphal threads around it, stealing sugars from the captive cell. The fungus in this kidnapping, probably from the Ascomycota phylum (think of cup mushrooms) is called the mycobiont. The green cell, the sugar maker, called the photobiont, could have been algae or cyanobacteria. The only thing it gained was a little home, a place to live propped up from the ground, protected from the sun and drying out, and from being eaten. No one knows whether the photobiont liked this or not, but the relationship has endured.
Reluctant to grow without each other, and almost impossible to cultivate in gardens or the lab, they have become their own species. Although, since only the fungal partner reproduces sexually, all lichens are classified as fungi. If a lichenized fungal spore hits the proper substrate and begins to grow, yet does not find an algal partner, it is toast — done with.
Lichens can grow where no one else can. Extremophiles, they are found on top of mountains on bare rock where they begin to break down tiny grains of what will become soil. They are found just below the mountaintops hanging from craggy spruce and fir, across the tundra where they feed caribou and reindeer, on abandoned trucks in the forest, in the desert, in the tropics and near the poles. They need a little water and some sun, but not too much. They do not care for pollution. They are exquisitely beautiful when seen up close.
Maybe lichens can teach us something about persistence and patience and the importance of partnerships, no matter how flawed or unequal. I am ready take all the lessons I can get for a better 2021.
Micki Colbeck, of Strafford, is an artist, a conservation biologist and a member of the Strafford Conservation Commission. Write to her at mjcolbeck@gmail.com.