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Getting Acquainted with Lichens

Getting Acquainted with Lichens

Letharia vulpicida

Learning about lichens is fun and adds a new dimension to your time outdoors.  But what is a lichen?  And how is it different from a moss?

To a biologist, the answer is simple: a moss is a plant and a lichen is a partnership between a fungus and algae or cyanobacteria (formerly known as blue-green algae).  But that may not help you, since you won’t see the algae or cyanobacteria with your naked eye.

So here is a general rule of thumb: Mosses are often grass green and lichens are every other shade of green, or brown, grey, orange, yellow; you get the idea.

You can find lichens almost anywhere, and it is surprising how many you can find growing on trees and shrubs in your own neighborhood.

We are fortunate to have an excellent book in our region to help you learn their names: Macrolichens of the Pacific Northwest, by Bruce McCune and Linda Geiser.  It has color photos of over 200 lichens along with a key and information about each species.

Some good news about lichen identification?  They are pretty easy to identify to the genus level.

A microscope or a chemical test will sometimes help you determine the species within the genus, but you don’t really need to know the species to enjoy finding a new lichen (or at least I don’t).

Bryoria fremontii

What name do you think best describes this lichen? horsehair lichen? bear hair? or black tree lichen? Photographer: Don Schaechtel, all rights reserved.

Lichens don’t always have widely accepted common names, so you may need to use some scientific names.  For example, the genus Bryoria, which is the brown lichen you see hanging from conifers in the mountains, has common names of horsehair lichen, bear hair, and black tree lichen.

But take heart, the tufted, chartreuse-colored lichen you see in eastside forests or model train sets is called wolf lichen no matter who you talk to, although a lichenologist will call it Letharia.

Lichens have three growth forms and learning these forms makes identification easier.  The three growth forms are

  • Crustose
  • Foliose
  • Fruticose.

Crustose Lichens

You are probably familiar with crustose lichens (think crusts).  These lichens are so firmly attached to their substrate that they can’t be separated from it.  One of my favorites is map lichen, which grows on rocks in alpine areas.  It has a great scientific name too: Rhizocarpon geographicum.

Foliose Lichens

Foliose lichens are leaf-like (think foliage) and come in lots of sizes.  The genus Lobaria (lung lichen) may measure six inches across.  On a smaller scale, you can find Parmelia (shield lichen) on the bark of trees and shrubs.  It is attached to the bark with Velcro-like hooks called rhizines.  Some foliose lichens have very small lobes, and almost look crustose, but they can be removed from their substrate.

Fruticose Lichens

Cladonia sp. a reindeer lichen

Reindeer lichen is a tufted fruticose lichen. Photographer: Don Schaechtel, all rights reserved.

Fruticose lichens are brush-like and often do not have a distinct top and bottom like foliose lichens.  They can be tufted, pendulous, or squamulose.

  • Tufted

A tufted fruticose lichen is one like reindeer lichen, which is having a genus identity crisis (is it Cladina or Cladonia?).  It is found in tundra throughout the world, and really is eaten by reindeer, but only when other food sources are scarce.  It forms beautiful mats that you can find in the Olympic and Cascade mountains.

  • Pendulous

Lichens that hang down from trees, such as Bryoria and Alectoria, commonly known as witch’s hair, are examples of pendulous lichens.

  • Squamulose

    podetia on Cladonia

    Fruiting structures called podetia are shown on this Cladonia sp. Photographer: Don Schaechtel, all rights reserved.

Squamulose lichens, such as the genus Cladonia, are often found on stumps, and are always a treat to find.  Many have fruiting structures, called podetia, that are shaped like small cups.  The common name for one of these species is false pixie cups.

An easy way to start learning about lichens is to collect specimens you find on the ground after a windstorm.  You will find them unattached and on fallen branches, where often three or more species are represented.

Lichens dry nicely and you can keep them in a paper bag or on your windowsill.  You can even staple fresh ones to trees and shrubs to start your own living collection.

Lecanora, a crustose lichen

Lecanora is a crustose lichen. Photographer: Don Schaechtel, all rights reserved.

Or you can just watch them grow, even on the sidewalk, where you can find a species of Lecanora, which I mistook for years as spilled paint.

This just scratches the surface of the lichen world.  No matter how you choose to enjoy lichens they are sure to delight.

Do you have any favorite lichens or lichen stories?


Top photo is the common chartreuse-colored lichen you see in eastside forests 
called wolf lichen (Letharia vulpicida). Photographer:  Don Schaechtel, all rightsreserved.