In his book A Short History of Nearly Everything author Bill Bryson philosophizes about the meaning of life and lichen. He explains “It is easy to overlook this thought that life just is. As humans we are inclined to feel that life must have a point. We have plans and aspirations and desires. We want to take constant advantage of the intoxicating existence we’ve been endowed with.
But what’s life to a lichen? Yet its impulse to exist, to be, is every bit as strong as ours — arguably even stronger. If I were told that I had to spend decades being a furry growth on a rock in the woods, I believe I would lose the will to go on. Lichens don’t. Like virtually all living things, they will suffer any hardship, endure any insult for a moment’s additional existence. Life, in short, just wants to be.”
Lichens don’t seem to agonize over the question of whether to be or not to be. Living innocuously on many surfaces, they lack the drama, dreams and desires of humans, but nevertheless they have a fascinating existence.
Longevity is one of their key attributes to admire, considering that some individual lichen have lived for centuries. They also have diversity and variety going for them: more than 15,000 species of lichen have been named worldwide, and on our little Island upwards of 150 have been identified. Of these, the bright yellow ones have recently caught my eye.
While species of yellow lichen can be found on trees, some varieties have a predilection for rocks. Notice the bright yellow types on rocks, walls and especially gravestones.
One species that favors rocky surfaces is Xanthoria parietina. Though most species of lichen only have a scientific name, this one is has a plethora of common ones, including yellow wall lichen, yellow splash lichen, shore lichen, golden shield lichen, maritime sunburst lichen, yellow scale lichen and even common orange lichen, since it sometimes manifests itself in orange hues. This yellow lichen is generally found near the shore and in the sun. Lichen is a composite organism made up of an alga and fungus. Xanthoria parietina is particularly adapted to a sunny spot because its fungal component produces a compound that acts as a sunscreen of sorts for its algal component. Way to cooperate and take advantage of a sunny niche!
Even more intriguing is its affinity and tolerance for nitrogen. Though all lichen are sensitive to pollution and are therefore indicators of air quality, different species exhibit different levels of heartiness. Yellow wall lichen thrives in nitrogen-rich environments. It does well on cliffs where bird droppings enrich the rocky substrate. And it flourishes near farms and livestock, which also add nitrogen to the surrounding environment.
There are other varieties of lichen that intrigue with their yellow pigments, including gold dust lichen, wolf lichen, lemon lichen and sulfur fire dot lichen. The last is especially fond of limestone, sandstone and concrete, which would explain its abundance on stone and in cemeteries.
Wolf lichen merits a mention and continues the association with death. This variety produces a toxin, vulpinic acid, which has been used for poison arrowheads and to kill wolves and foxes. In Europe, wolf lichen was mixed with bait. When animals ate the bait, the toxin would then cause paralysis of the respiratory organs. Thus, some care is called for when handling those particular lichen.
So while one could admire the sunny disposition of these bright lichens, they do have a dark side. This duality of their good and bad nature can even be epitomized by their color: while Vincent Van Gogh enthused “How wonderful yellow is,” Edgar Degas grumbled “What a horrible thing yellow is.”
We’ll give David Attenborough the last word. He realized that lichens’ intent is neither good nor evil, nor intended to please or displease anyone, “They simply exist,” he said, “testifying to the moving fact that life even at its simplest level occurs, apparently, for its own sake.”
Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown.