Exploring the World of Lichen with Shelly Benson

Photo by Pepperwood volunteer John Hibbard.

Lichens in our region are often seen on oak trees, covering their branches with a frosty white-green color or dangling down like Spanish moss. But did you know they are actually composite organisms consisting of a fungus and a photosynthetic organism (usually a green algae or a bacteria)? Sonoma County lichenologist Shelly Benson is president of the California Lichen Society has been studying lichen for 14 years. Pepperwood's Education Director Sandi Funke asked Shelly some questions about these fascinating life forms and how she got involved with them.

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How did you get into studying lichens?

Somewhat by accident…a summer job as a botanist on an ecological research project gave me some experience identifying lichens. It turns out that once you have a little experience in this area you’re way ahead of the rest of the competition. I landed several other jobs that required lichen identification skills, including climbing trees in Canada to study arboreal lichens. I ended up staying in Canada to complete my graduate research on arboreal lichen ecology. When I moved to California, I got involved in the California Lichen Society and continue to work with lichens.

Photo by Joel Cervantes.

Why do you think lichens are important to pay attention to?

Many ecologists will say that they can read the landscape by observing which plants grow where. The same is true for lichens. Lichens are sensitive to microclimate conditions and respond to gradients in temperature and moisture. The mix of lichen species growing near the coast is distinctly different than the mix of species growing in the Central Valley, which is distinctly different than the mix of species growing in the foothills of the Sierra Nevada Mountains. Additionally, lichen community composition shifts in a similar way in response to an air quality gradient. Some lichen species have been identified as indicators of clean air and others are known to indicate elevated levels of nitrogen-based pollutants. Observing the relative proportion of pollution-sensitive lichens to pollution-tolerant lichens can inform you about the air quality in your area. I find the process of becoming lichen literate fascinating!

Photo by Joel Cervantes.

How hard is it to differentiate between different types of lichens?

For the most part, if you have a good eye for detail, it is pretty easy to differentiate between different species of lichens. Once you learn the various lichen structures to look for, you’ll be able to sort out different species. However, putting a name on each of those different lichens is a little more difficult. One of the biggest challenges is finding a key that works well for your area. Currently, there is no lichen equivalent to the Jepson Manual, a key to the vascular plants of California. I often use keys from several different regions (e.g. the Pacific Northwest and the Dessert Southwest) to identify a specimen collected from the greater San Francisco Bay Area. Additionally, some lichens require the use of chemical tests for identification.

What is one of your favorite lichens and why?

Lace lichen, Ramalina menziesii, is a favorite lichen of mine.  It is one of the pale greenish hair-like lichens that drape the branches of trees throughout western California. The architecture of this lichen is amazing! Many of the lichen’s long, slender strands have lobe-like branches with a beautifully intricate lace-like pattern. The beauty of this lichen and its wide distribution throughout the state are reasons why the California Lichen Society has started a campaign to make this the California state lichen.

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On Saturday, October 26th, 2013, Shelly will teach a class on lichen at Pepperwood. Click here to register or learn more about the class.