In these endless days of winter white, I hunger for something beyond monotonous gray or cerulean blue sky against bare branches, a brook so frozen over I hardly know it’s there, pines with drooping needles. Winter storms, raging winds, and the amount of ice has made snowshoeing difficult, even before the heavy snow hit.

When I can, I snowshoe through my woods, noting the plethora of birch seeds that cover the ground, providing food for the birds. The grouse are absent and the only tracks around (besides squirrels and deer) are those of snowshoe hares and cottontails. Although these two Lagomorph species are supposed to have different niches, both share this spot.

I pay close attention to the trunks of trees, identifying various species as I pass by, and I look for lichens that have fallen from the trees. I bring a few back to the house and give them a bath in warm water. I let them soak in the warmth until like frozen children, their color returns! Afterward, my brittle gray friends transform, some turning bright green, all soft and yielding. They are now photosynthesizing, and to me at least, they seem to glow. One of my favorites, the lichen I call “wrinkled lettuce”, recently became a piece of prose:

When Lichen Comes to Life

When wrinkled lettuce 

skin is torn from limbs,

blown by bitter winds

wet snow becomes

its resting place.

 

If the deer don’t

find it first

I’ll take some home.

 

In a bowl of

warm water

s/he springs to life –

Fluted edges,

sage and crimson,

burnt sienna, umber,

I marvel,

offer refuge –

placing supple green

on emerald

tree branches, 

gifting friends

with respite

from winter

white and cold.

 

Crisped Creations!

Four billion years

of knowledge hidden

by those folds.

In the stillness

that settles after

any storm 

I’ll gaze upon

another miracle –

both

animal and plant – 

Fungi and

Algae living in

Harmony –

Rejoicing in

Difference.

 

Each provides  

what is needed

for the other.

Air to breathe.

Support.

This is more

than friendship.

Symbiosis.

 

Most don’t even

know you exist.

But you protect

Spruce and Pine –

provide immunity,

heal wounds,

call out warnings 

from the tallest trees,

your home. 

 

The picture of wrinkled lettuce is a foliose or leafy lichen named: Platismatia tuckermanii. Highly sensitive to air pollution, it will not grow in toxic air. Thankfully, it still falls from the highest branches of the pines and spruces in my woods, although not in abundance or size like it once did.

A troubling shift.

So what exactly is a lichen? Lichens are made up of two organisms. One is a fungus. 

Fungi are in a separate kingdom from plants. They don’t contain chlorophyll, so must rely on other organisms for food. Most decompose organic matter, and their barely visible mycelial threads run just under the surface in temperate areas and are microscopic in deserts, but this skin covers the entire earth. Mycorrhizal (symbiotic) mycelium is responsible for communication,  transporting water, carbon, and nutrients between trees and plants in the forest.

Algae are classified in a kingdom that is separate from plants and fungi. There are several types of algae: green, brown, red, gold. They can survive in saltwater and in freshwater, and in any environment, if attached to lichen. 

Cyanobacteria are part of the bacterial kingdom. They have to live in water. Sometimes they pair up with an alga and a fungus to partner with lichen.

It’s important not to confuse lichens with moss. Although both are non–vascular plants, meaning that they lack the tissues for transporting water/nutrients throughout the plant, neither do they have roots – the mosses have tiny leaves and are called bryophytes. Mosses are believed to be the ancestors of the plants we have today.  

To recap, lichens are two organisms that function as a single stable unit. Lichens are made up of a fungus that is living in a symbiotic relationship with an alga and/or a cyanobacterium. The dominant partner is the fungus, which gives the lichen the majority of its characteristics, from its shape to its fruiting bodies, tasty mushrooms. There are about 17,000 or more species of lichen – the statistics vary.

Fungi cannot photosynthesize because they lack chlorophyll but they are very clever; they have paired up with algae (and sometimes with cyanobacteria) who can harvest light from the sun and make carbohydrates, fats, and/or proteins.

Cyanobacteria (when present) also provide fungi with the additional benefit of being able to convert nitrogen to ammonia, which is a more useable form of this element (nitrogen fixation). In return for providing the fungi with food algae/cyanobacteria also offer protection from damaging ultraviolet rays, sometimes forming a shell with pigments that absorb the light. The fungal partner is composed of filaments that are known as hyphae.

The hyphae branch in every direction, but grow as solitary tips. Lichens can survive extreme conditions. Four hundred and eighty–five million years ago, lichens were probably the first living being to grow on rocks. They helped to break down stone to create the soil needed by more complex plants. 

Many scientists believe that lichens arrived on land before the vascular plants did, but lately, this idea has become more controversial. Some say mosses (also non-vascular) came first. It’s important to remember that science is more about the process of discovery so the ‘facts’ and context are always changing. What’s important is the antiquity of both organisms. Both have been around for 300 or 400 million years!

The fungal part of a lichen is known as the microbiont and the algal or cyanobacterial component is known as the photobiont. The thallus, or body, gives the lichen its outer appearance. What fascinates me is that these two (or three) actually have to choose each other, and after they do, they live in a symbiotic (mutualistic) relationship for the rest of their long lives as two or more organisms who can no longer survive on their own. 

There are different forms of lichens. For example, foliose lichen looks flat and leafy; fruticose lichen has a wavy tufted appearance, squamulose lichen has flat overlapping scales, and crustose lichen forms a tightly attached crust.

When lichens are dry or desiccated they look drab, brown, or blackish in color, but once wet, the fungal cells become transparent and the colors of the green algae or the darker but no less astonishing blue-gray colors of the cyanobacteria shine through. The lichens are completely transformed from withered dead-looking organisms to living beings with vibrant hues in less than ten minutes when put in water.

Lichens are compelling “creatures” who have many important functions. I have already mentioned that they can fix nitrogen, and they can break down the surface of rock-releasing minerals and chemicals that will eventually create soil for other plants. They provide food for deer, moose, caribou, reindeer, and other animals.

The life cycles of many native animals are intricately tied to lichens. For example, Ruby-throated hummingbirds line their nests with lichen, some insects protect themselves from predators by looking like lichens. Lichens produce unique biochemicals to fend off herbivores, prevent freezing, and stop seeds from germinating in their soft, moist tissue.

Many people don’t know that lichens possess antimicrobial, anti-fungal, anti-bacterial, and anti-viral properties that have been used by Indigenous peoples for thousands of years to treat various illnesses. I make a tincture out of Usnea, a pale green lichen that helps me with respiratory issues when I have a cold. Lichens absorb pollutants like heavy metals, carbon, and sulfur, and when extracted, give us an indication of the levels of these pollutants in the atmosphere (Bio-monitoring). 

Some lichens, like my wrinkled lettuce lichen, can’t tolerate air pollution, as already mentioned, while others, like the crusty lichens of the desert, are more forgiving. Another important function of lichens is that they provide a mode of survival in harsh environments where algae cannot normally survive (due to lack of any water).

Finally, I think lichens are important because they are so beautiful to look at, a golden orange, lemon, sage, sea, sap green, burnt sienna, umber, mole brown feast for any artist’s eyes. I have an old spruce that is full of Usnea, a sea-green lichen that cascades over the sides of its many encrusted branches. I can lose myself in this unruly sky tangle until my arching neck begins to ache, returning me to the present.

There are approximately 3,600 species of lichens in North America, and those are just the ones we know about. New discoveries are being made every year. Lichens 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.

I hope I have intrigued the discerning reader to pay more attention to lichens during these long winter months, when walking or snowshoeing in the woods offers an opportunity that is almost always lost when spring blossoms in all her generous green glory, making it so difficult to focus on such subtle creaturely organisms. And perhaps like me, you might find a lichen that isn’t even supposed to grow on the east coast at all!

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