Part 1
With more than 600 species of lichens in Maine, photographing and gathering a few, some for wreaths, and one for a tincture, is one of my favorite winter past times. During the cold months, I am increasingly starved for color depending upon occasional sunrises, alpine glow, and sunsets for intensity. Once we had deep green evergreen mountains, but all that is changing. Drab brown fuzz and skidder marks now cover the stripped mountains around my house. Lichens are an endless source for inspiration during these months because they glow green brown and gold with winter precipitation regardless of whether it is rain, ice, or snow.
In this article, I am going to discuss a couple of different lichens that are favorites of mine. We have so many and seeking out these complex organisms can become a passion for others as it has for me! Some lichens are tolerant of pollution, others are disappearing; a result of decreasing air purity in Maine.
What follows is some general information about lichens that are reputed by some to be the first organisms to colonize land roughly 400 – 450 million years ago (the timeline keeps changing). The point is that lichens are ancient living beings who developed incredible strategies for moving from the sea to inhabit the rocks they found on land. Lichens are responsible for creating the first soil because they break down stone.
Lichens are composed of two or more dissimilar organisms that form a mutually beneficial (symbiotic) relationship. Together they produce a new vegetative body that is called a thallus. The life forms are composed of fungi and green algae and/or cyanobacteria. Fungal filaments make up about 80% of the lichen body. The fungus forms the outer surface to provide support and protection, absorb moisture, and collect minerals from the air. Since the fungus cannot produce its own food, it is dependent upon algae to provide this essential function. Green algae and cyanobacteria possess the green pigment chlorophyll, which is essential for photosynthesis. When surrounded by fungi, algae/cyanobacteria provide the nourishment necessary to enable the lichens to exist and sustain themselves. Neither can survive without the other (s).
Unlike plants, lichens do not have leaves, stems, roots, or a waxy outer cuticle to control body water content. Lichens continue to grow during periods when dew, mist, and rainwater are present but during a summer dry period they often become dormant (photosynthesis ceases) until the next rainfall. Miniscule mineral particles that are carried by the wind during wet conditions are dissolved and absorbed by the lichen. They are able to photosynthesize in the winter as long as temperatures aren’t frigid.
Lichens produce their own food using sunlight, water, and air and do not feed on tree bark. The lichen bodies are attached to the outer bark and remain on the surface. Their rhizines (not roots) typically do not penetrate deep enough into the inner bark to cause harm to the trees they inhabit. This latter information is particularly important because many people associate lichen with dying trees and cut them down. I know I once did…
When I first came to this area I felI in love with a large ‘dying spruce’ that dripped Usnea lichen from every branch. Because I only remove trees that threaten the house, I left that one alone. I had no idea then, that almost forty years later, that this same tree would still be standing, photosynthesizing away with Usnea hugging its branches, or wearing beards, casting threadlike tendrils in every direction.
It is true that the lower branches of the spruce are bare, (allowing the lichen to absorb more sunlight) but above the limbs and tall spires are covered with needles. My point is that even if a tree is dying, the lichen inhabiting lower branches is not killing the tree. Instead, lichens keep the tree photosynthesizing for many years, so maybe it is best to simply leave the tree alone as I have continued to do.
Most lichens like some mosses grow prolifically on trees. I find Usnea extraordinarily beautiful; clumps of silky hair or delicate reindeer-like branches sway in light winds…Often, while gazing up into my spruce’s branches, acclaimed author Terry Tempest Williams’s words will materialize out of thin air. “Beauty is not a luxury. It is a strategy for survival.” Indeed.
However, it’s important to note that there are certain fungi that operate independently outside a lichen body that will penetrate tree wounds or dead wood and feed on a host plant. The filaments of the fungal body will reside inside the tree tissue with only the fruiting bodies visible on the surface.
There are at least 13,000 – 20, 000 species of lichens living throughout the world. Lichen species are so numerous and diverse that there are individual exceptions to most general statements made about them. Scientific knowledge about lichens has expanded significantly during the past few decades, and new discoveries continue.
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