Lichen Basics

Day 106: This is the type of dry reading you're likely to see on official NPS pages from here on out, but at least it's science.

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Those of us who live in the Pacific Northwest are fortunate to have a wide variety of lichen species in our forests. Although lichens appear in almost every geographic region of North America, the leafier types are more abundant on the northwest and northeast coasts. Many of them are mistakenly called "mosses," but in fact they are complex symbiotic organisms. One of the most exciting revelations in the field of lichenology occurred this year when a third component was identified in the classic "fungus/algae" pairing: yeast. Let's look more closely at some common PNW lichens and learn a little of the specialized terminology which describes them.

There are three basic types of lichen: foliose, fruticose and crustose. Foliose ("FOH-lee-ose") lichens are "leafy" (think "foliage"). Platismatia (upper left) is an excellent example. Fruticose ("FROO-ti-cose") lichens are bushy or shrubby, or have a three-dimensional structure which often includes round stalks topped by cups or knobs. The photo in the upper right shows an example of Cladonia, a classic fruticose family.

Sometimes, it is difficult to assign a lichen to a specific category. The lower left image shows a Hypogymnia. The Hypogymnias are classified as "foliose-fruticose." The last type of lichen is called crustose ("CRUST-ose"), and as you might guess, it forms a crust which adheres tightly to trees and rocks. Crustose lichens often exhibit small fruiting bodies such as those which appear on Ochrolechia (lower right).

Pseudohydnum Winter Reprise

Day 105: With a gag order in place to prevent me from talking about anything to do with climate change on our official Park pages, I reviewed my scheduled posts last night to be sure I hadn't said anything "seditious" in my botanical discussions...no mention of warmer summer temperatures or of lichens growing only where the air is unpolluted, no references to animals changing their ranges in order to adapt to diminishing food sources. As a naturalist, I find it very difficult to keep those things out of any communication since they are so close to my heart. It's going to be tough to keep my weekly feature going when I'm limited to engaging people with plain and undeniable statements: "This is a lichen. We have a lot of them in the Pacific Northwest." Stop right there. I mustn't say, "...because the on-shore flow keeps the air in our forests clean."

I've been mulling over what I can and can't do under the new regime. I decided that introducing some lichen basics would be safe, so to that end, I went out for a walk this morning to find examples of crustose, foliose and fruticose growth habits. I found them all, and got a bonus in person of the largest Pseudohydnum gelatinosum I've ever seen, a full three inches tall and two inches across. Usually, they're just little translucent jelly-blobs the size of your thumbnail. They can't be mistaken for anything else. They are the only white, translucent stalked fungus with "teeth" instead of gills. They're great. I mean, really. Usually tiny, but great.

Wait...who's knocking on my door? Is that the censor? Oh, dear. I said "tiny," didn't I?