Lichen Land From Maine to New Mexico
A couple of weeks ago I had to cut down a sixty seven year old White pine near my house. And yesterday I found the most beautiful lichen that must have fallen from that tree, something called Fringed Wrinkle lichen, a lichen that thrives in the uppermost branches of Eastern white pine and hemlock trees.
I am frankly fascinated by lichen. Because this summer has been so hot and dry I have spent more time in the woods than usual. Mushrooms have been scarce and I have been looking at various lichens marveling over their ability to deal with drought conditions. During dry spells lichen become dry and crispy but don’t expire. Lichens grow on rocks, trees, and in the soils in many different environments. Around the house I must have at least twenty different types of lichen, maybe more. I haven’t counted all of them.
Lichen is composed of two organisms that arise in a symbiotic relationship. One is an alga or cyanobacteria and the other is a fungus. The algae live among the filaments of fungi. Evidently the fungus is the predominant partner because it determines the majority of the alga’s characteristics, from its curious shapes to its fruiting/spore producing bodies. Some lichens have more than one algal partner.
Fungi depend upon the algae for nutrients since they do not contain chlorophyll and cannot photosynthesize. Algae and cyanobacteria can manufacture carbohydrates with the help of light via the process of photosynthesis. By contrast, fungi do not make their own carbohydrates. Every fungus needs existing organic matter from which to obtain carbon. Fungi provide water for the algae and decompose the organic matter around them. When looked at microscopically the fungal partner is composed of filaments called hyphae. The hyphae grow by extension – branching and fusing. In lichens some of the carbohydrates produced by the algae are, of course, used by the alga but some is ‘harvested’ by the fungus.
There are 20,000 lichens on earth. They can be found growing in almost all parts of the terrestrial world, from the ice-free polar areas to the tropics, from tropical rainforests to those desert areas free of mobile sand dunes. While generally terrestrial a few aquatic lichens are known. The surfaces (substrates) on which lichens grow vary from soil, rock, wood, bone to the man-made concrete, glass, canvas, metal etc.
Amazingly, Lichens possess structures not formed by either of the partners and produce chemicals usually absent when the fungus or the alga are cultivated separately and so lichens are more than a sum of their parts. In fact, lichens synthesize over 800 substances, many of them not found elsewhere in nature. That they produce powerful antiviral properties that protect them and could be useful to humans is a fact. Why are we not studying them?
Lichens come in many sizes forms and colors. Around here some of my favorites are the bearded lichens that hang from the dying spruce down by the brook, and even in drought they keep their sage gray green color. Others like the Fringed Wrinkle lichen intrigue me because they are bi –colored and so wave-like in appearance. The neatly puffed shape of Reindeer moss, (yes, it is a lichen) is another. There is a pale pink lichen that grows along my road and the crimson topped British Soldiers is yet another much appreciated lichen species.
As much as I love the gray green lichens my absolutely favorite lichen is orange. Sunburst lichens grow from the coast of Maine to New Mexico. When I lived on Monhegan island I was surrounded by these lichens which grow on rock outcroppings near the sea. I don’t recall where I have seen any sunburst lichen around here except in graveyards. Parietin, the pigment that colors sunbursts intensifies under sunlight. The stronger the solar irradiance, the denser the pigment. When growing in the woods most sunburst lichens don’t need sunblock so they are more yellow than orange. Parietin protects the sensitive algal partner from exposure to ultraviolet rays. This pigment also protects the slow growing lichen from slugs and other herbivores who otherwise might denude them because of the way the pigment tastes.
On the porch of the casita in New Mexico I have a slightly squared stone that a friend found on a hike and gave me a couple of years ago that has a thin crust of orange lichen on it. I have watered it from time to time noting that despite my attention the color has dimmed. Is this because it came from the high country where the air is less congested with particles? I don’t know.
For a naturalist like me sunburst lichens help me to get a reading on who might have once been in the area. At the seacoast the color orange suggests that seabirds were present; farther inland the presence of orange lichen over a crevice might indicate a coyote or fox den. Orange lichen appearing on a branch of spruce or balsam provides me with evidence that an owl might have roosted here for a time. Newly laid dung will provide the substrate for a colony of orange lichen to appear in a few years.
Lichens are usually described as having a leaf -like (like my fringed friend), crusty, or branching/shrublike forms. Lichens often play an important part in the weathering of rocks. When lichens attach to rocks, they retain moisture and are instrumental in breaking down the stone. This process is an essential component for producing soil in a barren environment, but it takes years.
In the desert it is easy to spot dark clumpy soil areas, which are actually a layer which can include cyanobacteria, lichens, mosses, green algae, microfungi, and bacteria. This living biomass binds particles of soil, reduces erosion, fixes nitrogen, and can add organic matter. These areas are very fragile and even a footstep reduces their functioning which can take years to rebuild. In Abiquiu, the local cattle trample this delicate ground with impunity.
Lichens are widely used for many different purposes throughout the world. The most common use is dye production. Litmus paper is made from a dye mixture extracted from the Rocella species which is then applied to filter paper. Dyes used for clothing were used in the Scottish Highlands and produced red, orange, brown, and yellow. Purple dyes used throughout Europe from the 15ththrough 17thcenturies were extracted from lichens.
Many lichens have been used medicinally. A lichen’s usefulness as a medicine is often related to the lichen secondary compounds that are abundant in most lichen. It is estimated that 50-percent of all lichen species have antibiotic properties. Many lichen extracts have been found to be effective in killing the bacteria that cause boils, scarlet fever, and pneumonia.
Lichen are sensitive to atmospheric pollution including nitrogen and sulfur emissions that lead to acid rain, as well as toxic lead and mercury emissions. This sensitivity makes lichen a valuable biological indicator of air quality.
Some sensitive lichen species develop structural changes in response to air pollution including reduced photosynthesis and bleaching. Pollution can also cause the death of the lichen algae, discoloration and reduced growth of the lichen fungus, or kill a lichen completely. The most sensitive lichens are shrubby and leafy while the most tolerant lichens are crust-like lichens.
Lichens have been around for 250 million years and have learned how to cooperate and live in harmony. These fascinating and sometimes diminutive animal – plant ‘beings’ with their antibiotic/antiviral properties could be powerful teachers helping humans to develop medicines that could help with our current pandemic, as well as modeling the ability to cooperate despite ‘difference’ something our dominate culture has yet to learn.