Monday, March 25, 2013

We Like Lichens!

As members of the Ottawa Field Naturlists' Club (the oldest natural history club in Canada), the ADG and I recently attended a lichen workshop led by renowned, local lichenologist Irwin Brodo.  He gave a brief presentation on lichen basics, including a definition of just what the heck lichens are.

"The most significant thing about all lichens is that they are two plants, not one.  Each lichen plant body or 'thallus' is a biological twosome composed of a fungus living in intimate contact with an alga.  The relationship involves much more than the mere contact or even relative position of the constituents; it results in the formation of the entirely new, self-sufficient, functioning unit which gathers raw materials, manufactures food, conducts an exchange of of vitamins and growth substances, and often even reproduces as if it were a single plant."   Cooool!
Many lichens are highly sensitive to air pollution and the presence or lack of lichens in urban areas can be indicators of pollution levels in a city.
He discussed the the structure and different parts of lichens.
I thought the distinct algal layer was really interesting.
Rhizines are hair-like structures that anchor lichens to the substrate and they come in different shapes and sizes.
After the presentation we spent some time looking at various specimens under the microscope.  Irwin had a box of numbered but unlabeled samples for us to view, and a key to common, urban tree lichens of Eastern Ontario and Western Quebec.  Our challenge was to key out and correctly identify the lichens under our lens.
After two initial misidentifications, the ADG and I got on a roll and correctly identified four in a row.  Some lichens were best identified with the addition of sodium hypochloride or potassium hydroxide.  Applied to either the cortex or medulla, a colour reaction might occur changing the test area to yellow, orange or red depending on the genus and species, which was very helpful in getting a correct ID.
It was fascinating to look at the different lichens up close.  Many were stunningly beautiful under magnification, especially the specimens with fruiting bodies.
By the end of the afternoon, we both remarked about how tired we were.  I actually find plant keys to be exhausting because they require such focused attention.  Add to that a couple of hours staring into a microscope and it's no wonder we were ready for a nap!

It was a great way to spend a late-winter Sunday and I'm really glad to have had the opportunity to learn a little more about lichens.  I will definitely look more closely at these amazing organisms.  Next, I want to learn about which lichens are edible!

Here are just a few common, urban tree lichens you can find in the Ottawa area:

Evernia mesomorpha

Flavoparmelia caperata

Candelaria concolor

Graphis scripta

Phaeophysica rubropulchra

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