An Introduction to Lichens
The story goes something like this:
Annie Algae was a good cook, but she needed a place to live. Freddy Fungus had a nice house, but he didn’t know how to cook. A mutual friend introduced them to each other. Freddy invited Annie over to his house and she cooked a fabulous meal for both of them. They took a lichen to each other and lived happily ever after.
How to talk like a lichenologist
Many lichens do not have well-established common names. Wolf lichen (genus Letharia) is an exception. The genus Bryoria is more typical; common names include horsehair lichen, black tree lichen, and bear hair. So don’t be afraid to use scientific names for lichen genera. And don’t feel like you have to identify the species within the genus; sometimes it can only be determined with a chemical test or microscope.
Lichens can be grouped in three different forms:
Crustose lichens (think crust) are bonded to their substrate, such as rock or wood.
Foliose lichens (think foliage) have lobes with two definite sides.
Fruticose lichens (think shrublike) have branches, or stalks, or strands.
Most lichens have an outer cortex, which protects the algae cells on the inside.
The inside of a lichen is called the medulla, and is often white.
Some lichens are attached to their substrate with Velcro-like hooks called rhizines.
Lichens use several reproductive strategies:
Spores are produced in apothecia (a-po-the̒-ci-a), however spores only contain the fungus component and have to find the algae component (see story above).
Soredia are round balls of both fungus and algae cells that can start new lichens.
Isidia are wartlike growths that contain both fungus and algae cells that can break off to start new lichens.
To learn more about lichens
The best guidebook is Macrolichens of the Pacific Northwest, 2nd edition, by Bruce McCune and Linda Geiser (2009). It is available at amazon.com for $22. This book describes most foliose and fruticose lichens in Washington.
You will also want to invest in a good magnifying glass with at least 10X magnification.
If you want the definitive book on lichens it is Lichens of North America, by Brodo, Sharnoff, and Sharnoff (2001). It is available at amazon.com for $96.