Lichen growing on the trunk of a massive tree

Lichen: Colors and patterns of the forest you might have overlooked.

Written by Matt Pyster, a member of the SCA NH Americorps program – soon to be interpretive ranger at White lake and Ellacoya State Parks.

Lichen. These beautiful and oddly simplistic organisms are a focus of attention for me right now. Until recently I didn’t realize just how many types of lichen are in the forest around me. In fact, every photo in this blog post was taken on a short 4 minute walk in Bear Brook State Park, and all were within sight from the main pathway. 

Tiny black wriggling lines atop a white lichen, itself laying on top of the cracked bark of a tree.
Some of the colors and patterns weren’t visible until I got really close, like on this script lichen.

When fungi works synergistically with either algae or cyanobacteria (CB), we call the combination “lichen”. The fungi exists as a surface on which the algae/CB can live. In turn, the algae/CB provides the fungi with sugars that it creates through photosynthesis. Something that makes them really cool in my mind is that lichen can absorb all the water and nutrients they need…right from the air! This means they don’t have to be attached to the soil. Yup, you’ll find them growing on rocks, on branches, on telephone poles…pretty much everywhere. Here are a few photos of where I found them on my walk!

A light blue lichen attached like a crust on a boulder.
A vibrant blue lichen that grows everywhere
Light blue lichen attached to a fallen tree trunk
Greenshield lichen + at least one other type of lichen growing together.
Grey lichen pasted onto a boulder
Lichen can be grey too!

Question time… If lichen grow on trees, do they harm those trees? Would they gain anything from doing so? Think for a minute about what we learned in the last paragraph – and once you have thought about it, read on for the answer.

Lichen growing on the trunk of a massive tree
Lichen growing on the trunk of a massive tree – harm or harmless?

Lichen grow all over trees, dead and alive; however, they get water and nutrients from the air. This means they don’t need to steal nutrients from the surface they are attached to. So even though they may cover the bark of a tree, they are basically just “couch surfing” to get access to sunlight – no harm done. In fact, sometimes lichen help trees. Lichen can help prevent erosion of soil, and they can create new habitats for plants to grow in. The photo below shows an example of lichen unintentionally collecting debris and soil on top of a rock, thereby creating a microhabitat that a plant took advantage of!

A small plant growing in a microhabitat of soil and pine needles
Notice the green guy in the center of the picture!

One type of lichen, Rock tripe, is especially famous in US history. It has a rubbery texture, and is edible if cooked properly. In the winter of 1777 at Valley Forge, when George Washington and his men were freezing to death and running out of food, some of his men reported eating rock tripe to stay alive. Some species are considered a delicacy – but not the species GW and his men were likely eating. Delicious or disgusting, either way, it was food and helped fill the stomachs of those men.

Large leafy brown lichen, resembling flaps of leather clinging to a boulder.
Rock tripe can easily be as big as a hand.

Today, not many men are surviving off of rock tripe, but lichen are still appreciated in part for the beauty and depth they can add to the woods. I invite you to come out and see some of the diverse species and colors of lichen that color the forest here at Bear Brook State Park.


Discover Power of Parks SCA Interpreters

Discover the Power of Parks is presented by New Hampshire State Parks in collaboration with the Student Conservation Association and made possible by generous financial support from Eversource. The program offers a look into the natural world through hands-on programming. Interpretive programs focus on connecting participants with nature and building appreciation for New Hampshire's unmatched natural heritage. Programs include guided hikes, interpretive tours, and imaginative environmental workshops for children and families. Programs are offered free to guests with paid park admission fee. No pre-registration is required.

2 thoughts on “Lichen: Colors and patterns of the forest you might have overlooked.

  1. You should look into this deeper. I went to a seminar where the lecturer, who is an expert mycologist, explained that the two component theory falls short of the facts. In fact studies have shown that there is a third component that enables the system to work. I’m sorry I don’t have more than that. My memory isn’t what it once was.

    1. I did not realize that! I looked it up, and it appears that the third partner is…yeast! Yeast is another type of fungi, so now lichen are often two fungi + algae. It is not definite that all lichen have this three part symbiosis, but many do at the very least. The yeasts role is hypothesized to be producing chemicals that protect the lichen. I saw at least one way they protect is through production of toxins that prevent other creatures from eating or infecting the lichen.
      In addition, algae can also be replaced (or joined) by cyanobacteria (bacteria that can undergo photosynthesis). I left that out for sake of simplicity in my blog post, but it is some additional information if you are interested.

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