Red-tipped British soldiers lichen is found growing in a pile of granite boulders on April 21, in the woods outside of Bangor. Credit: Aislinn Sarnacki

Lichens are among the many fascinating and beautiful things found in the Maine outdoors, and they come in all colors, shapes, textures and sizes. Throughout the wilderness, lichens cling to boulders, wrap around tree trunks, trail from branches and pop up from the ground.

But what exactly are they?

Lichens are types of fungi that form relationships with algae or cyanobacteria to survive. In this partnership, the fungus usually acts as the house or shelter. In return, the algae or cyanobacteria produces food through photosynthesis.

When you start to look for them, you find that lichens are absolutely everywhere. Here are six in Maine that are easy to locate and interesting to look at — plus interesting stories about how they got their quirky names.

1. British soldiers lichen

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With pale green stalks topped with bright red fruiting bodies, the British soldiers lichen (scientific name: Cladonia cristatella) earned its common name because its red “caps” resemble the red hats worn by British soldiers during the American Revolutionary War. Native to the eastern half of North America, this lichen is common throughout Maine, and while it is small, its bright hue makes it easy to spot and identify.

There are a few look-alike lichens in the same genus, including lipstick powderhorn lichen (Cladonia macilenta) and red-fruited pixie cup (Cladonia pleurota). Both produce red fruiting bodies, but their structures are slightly different.

British soldier lichen is eaten by a variety of animals, from land snails to white-tailed deer, and can be found in damp forests — which explains why it’s so common in Maine. It often grows alongside other lichens, sprouting from damp, decaying wood and peat.

2. Old man’s beard

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Dangling from tree branches in long, crumpled, pale green strands, beard lichen — often referred to in Maine as “old man’s beard” — is a common sight in old forests throughout the state, especially along the coast. Often, when people point out this lichen, they are looking at several different but closely related species in the genus Usnea.

The classic old man’s beard, which forms in long strands (anywhere from 6 inches to 20 feet long) is Usnea longissima. Once common throughout the country, this species has become rare due to habitat loss and pollution, according to an online lichen profile published by the U.S. Forest Service. It is especially sensitive to air pollution. Therefore, when you find it, you know the air is clean. It’s normally found in the forest near bodies of water and grows in the tops of conifer trees.

Other species of bearded lichen in Maine include bushy beard lichen (Usnea strigosa), boreal beard lichen (Usnea subfloridana) and bristly beard lichen (Usnea hirta). These related lichens are similar in appearance but don’t grow to be as long as old man’s beard. Their structures are also slightly different.

3. Lung lichen

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Also known as tree lungwort, lung lichen (Lobaria pulmonaria) is a large, showy lichen that turns bright green when wet and a paler shade when dry. It’s usually found growing on tree trunks and boulders in humid, shady, forested areas. And it serves as an indicator for healthy ecosystems, according to a lichen profile published by the U.S. Forest Service.

Lung lichen’s scientific name, “pulmonaria,” is derived from the Latin word for lung. This is because its leafy appearance resembles the shape of a lung, with its many lobes and branches. In traditional medicine, this lichen has been used to treat respiratory ailments. This medicinal use has been attributed to the doctrine of signatures, an old belief that herbs resembling certain body parts can be used to treat ailments of those body parts.

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4. Pink earth lichen

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You don’t have to even walk into the forest to find this lichen. Pink earth lichen (dibaeis baeomyces) is often found growing along the sides of gravel roads, especially in clay-filled soil, according to the Consortium of North American Lichen Herbaria.

This lichen is easy to overlook because it is so small, but at close inspection, its alien-like structure is quite interesting. As its name implies, it produces pink (or orange or peach) flowering bodies, which are round and placed at the end of thin stalks. These protrude from a bumpy crust that’s pale green, gray or off-white.

This lichen does have a look-alike, icmadophila ericetorum, which is commonly known as candy lichen or fairy barf. This species tends to grow on a different surface — mainly rotting stumps, logs and peat. Also, its fruiting bodies are a bit flatter and tend to be closer to the crust, and sometimes grow directly on the crust.

5. Rock tripe

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Found covering the many boulders scattered across the Maine landscape, rock tripe (Umbilicaria mammulata) is a lichen that grows in smooth, leathery sheets. Often, this lichen will engulf the entire side of a boulder, making for quite a spectacle.

When touched, rock tripe has a stretch to it — almost like rubber. The side facing outward is brownish or green, while underneath, it’s velvety and black. It prefers moist, partially shaded habitats, according to an online resource by the Ohio Moss and Lichen Association.

Its common name refers to the lichen’s resemblance to tripe, which is a culinary dish produced from an animal stomach, according to a lichen profile published online by the Harvard Museum of Natural History. But rock tripe doesn’t just resemble food, it is food. In North America, rock tripe is viewed as an emergency survival food, while in other places it is viewed as a delicacy. In fact, George Washington’s troops were said to have gathered and boiled it for soup at Valley Forge, Pennsylvania, during the winter of 1777 to 1778.

6. Reindeer lichen

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Reindeer lichens are a group of similar lichen species in the genus Cladonia that are feasted upon by caribou or reindeer. These lichens form puffy, shrub-like clusters on the ground. In general, they occur in cool to cold climates, according to an extensive paper on reindeer lichen published by the U.S. Department of Agriculture. They are slow growing and long lived.

Because reindeer lichen only needs a thin layer of rocky soil or organic material (such as moss) to become established, it is often found in rocky areas and atop mountains, where soil is poor. In addition to being a food source for caribou, it may serve as food for voles and other small mammals. Like many other types of lichen, reindeer lichen is sensitive to pollution. Certain species serve as indicators for the presence of heavy metals and acid rain.

Now get outside and go find some lichen. Certain species, such as the bearded lichen and lung lichen, are visible year round. Keep your eyes peeled, and you won’t have to walk very far.

Aislinn Sarnacki can be reached at Follow her on Facebook:, Twitter: @1minhikegirl, and Instagram: @actoutdoors. Her guidebooks “Family Friendly Hikes in Maine,” “Maine Hikes Off the Beaten Path” and “Dog-Friendly Hikes in Maine” are available at local bookstores and wherever books are sold.

Aislinn Sarnacki

Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also...