HORT travels

Exploring the horticultural beauty in every adventure.

A Unique Relationship


Snow and Lichens in Tuscarora State Park PA

Snow and Lichens cover a boulder in Tuscarora State Park, PA

Seems as though spring is taking a bit longer to sprung. As I write this temperatures are dipping into the twenties. Though the tried and true late winter/early spring bloomers are slowly and cautiously making  an appearance there is still barely a sign of green bud or yellow flower around.

This is when I get antsy. Snow is gone, well, almost, snowboards have been packed away and the gardening tools have emerged. But the ground is still frozen and the soggy soil means I can’t even plant my peas yet. What is a plant person to do, sit and twiddle my thumbs until it Spring actually arrives?

Thumb twiddler I am not. Of course I start vegetable seeds in my basement in the ultimate act of optimism. One only does that if they have a firm belief that eventually the sun will come out and it will be warm enough to grow a tomato. But this time of year I also find myself exploring the early spring forest. Sure, witchhazels are blooming, and the earliest spring bulbs are starting to appear in the garden. But where is the green we are all waiting for? When I cannot find green buds swelling in vernal warmth I examine what green I can find and in my little speck of land that means lichens.

A variety of lichens encrust a boulder at Seneca Rocks in West Virginia

A variety of lichens encrust a boulder at Seneca Rocks in West Virginia

Different Colors:

Lichens come in all shades of green. From dusky mint green to the kelly green one expects in spring. You may remember from my accessories post that some even come in bright pink. Lichens come in many textures to from silky to puffy to mossy and lacey. But just what is a lichen? Lichens are those green spots on sides of trees and rocks. A while back a colleague taught me that a lichen occurs when “algae takes a likin’ to a fungus”. And that my friends, is exactly what a lichen is.

According to to a terrific publication about lichens published by the Minnesota Department of Natural Resources it wasn’t until the late 1800s that scientists figured out that these organisms were two organisms in one: algae and a fungus.

Because both of the organisms benefit from this relationship (well, that’s a nice idea isn’t it?) it is a symbiotic relationship. It is really quite interesting and you may have no idea that all of this is going on when you are just looking at a lichen on a tree. According to author Todd Whitesel, the fungus provides the “house” for the algae. The fungus protects the algae from the weather and makes up 90% of the lichen. The remaining 10% of the lichen is the algae. These are water loving organisms filled with chlorophyll, green pigment, which they use to turn energy from the sun into food for the organism. Not all algae and not all fungus can form these mutually beneficial relationships, just like people, it takes the perfect match.

Lichens on a Michigan Forest  Floor

Reindeer Lichen (Fruticose) on a Michigan Forest Floor

Lichens can be found all over the world growing on anything from trees to boulders to man-made structures. Some growing in hot sunny areas, like those mentioned in the accessories post, protect themselves with pigments that act as sunscreen. So you may see pink, yellow, orange or red lichens in addition to the green.

Different Uses:

Those protective pigments in lichens are used by some people to dye fabric. Components of lichens are being explored for potential as new “natural” herbicides. Many wildlife species depend on lichens as a food source in winter months and harsh conditions when not much other food is available. Animals from wild turkeys to caribou have been recorded eating these trunk hugging organisms. Flying squirrel nests made completely of lichen have been found around the country and lichen make up a significant portion of hummingbird nests.

Different Shapes

Animals will find some lichens easier to make use of than others, much of that depends on shape. Lichens are divided into three categories based on their growing habits:

Crustose: Form a crust on rocks and can even be found growing in glaciers.

Crustose Lichens on Boulder in West Virginia

Crustose Lichens on Boulder in West Virginia

Foliose: Leaf-like

Fruticose: Bushy, resembling miniature trees.

Fruticose Lichen (and others) on a trunk in Tuscarora State Park, PA

Fruticose Lichen (and others) on a trunk in Tuscarora State Park, PA

Some people believe lichens living on tree trunks is a sign of the tree’s poor health or that the lichens are damaging the tree in some way. This is not true. The lichens are merely using the tree for support for access to the water and sun it needs to thrive. In fact, finding lichens on your trees and rocks is great! Lichens are considered an indicator species, that is, they are an indicator of healthy environmental conditions. Lichens do best where the air is clean and the rain isn’t acidic. If you have lichens chances are you have clean air and water. This is why you see lichens frequently in forests and not so frequently in cities.

Signs of clean air and water, lichen covered boulders dot the woodland.

Signs of clean air and water, lichen covered boulders dot the woodland.

For those of you that panic when gray snowy days erase all memory of green there is no need to get antsy and think spring will never come. There is always something spectacular going on in nature and in your garden. It is all a matter of perspective and just how close you want to get to your plants to find it. Don’t let this cold keep you in, don’t let a lack of green extend your winter blues – get on out into the woods and find the many shades of green and gray and pink just waiting be discovered on a trunk or boulder near you. (Here is handy online key to identifying lichens if you are so inclined.)

For those of us that like the snow, some of these lichens can resemble large snowflakes and help us think cool thoughts when those awful humid days of summer are upon us:

Want to learn more about lichens? The Smithsonian’s National Museum of Natural History houses the Lichen Collection of the US National Herbarium. Here more than 250,000 specimens are housed, making this the largest lichen collection in North America.

6 thoughts on “A Unique Relationship

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  5. The lichen photos are beautiful, and I am glad to hear my trees are healthy. Thank you for your always interesting website!

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