What is a lichen? A lichen is made up of fungus and other components like algae or cyanobacteria (blue-green algae). In addition, there are yeasts and chemical components. Lichenologists like to say, a lichen is a fungus that has turned to farming. The fungus uses the algae or cyanobacteria to get its nutrients. If you attempted to grow the fungus and algae separately, they would look totally different.
In the field I assign a number. I take measurements. Then note the color of the lichen. In this case, it is pale gray-green. This is Paramotrema simulans.When wetting down a foliose lichen, it usually turns green. The green algae is just below the upper cortex or thallus. Thus can shine through. And when it rains, lots of the lichens turn green. Some bright green!After the overall photos, the cutting begins.Chemical tests are performed to test for the reactions. These tests are key for ID’ing. I always take a before photo. This way there is no doubt about the color comparison reaction.This one had a yellow reaction on the upper cortex. The medulla or the inside layer was negative or no color change.I write all information down on the collection envelope and in a spreadsheet.So here is a cut section of the above lichen. Upper cortex is on top. Next the green algae layer. Followed by the medulla (hypha) and the lower cortex. And then the rhizines (holdfasts) on bottom. Rhizines are not roots.Indeed a closer look is needed under the microscope. You never know what you may find. For example, other critters like a water bear. 🙂Soredia were on the Paramotrema simulans lichen edges. So this is a means of asexual reproduction. Each soredium has a few algal cells. For a fungus to be a lichenized it needs to be the “farmer”. On this particular foliose lichen, it did not have the fruiting bodies (apothecia). Further down an example of the apothecia will be shown. A microscopic view of the green algae. No swimming water bears that day. In fact, I have only found one water bear. Always hopeful.Here is Parmotrema perforatum or possibly Parmotrema preperforatum. So I do not have the right chemicals to preform the needed test to distinguish the two. However, the little brown cups (apothecia – fruiting bodies) are where the spores are produced for sexual reproduction. Lichens can have one to several combinations for reproduction.A “classic” foliose lichen modeled in food. Starting at the top, the Reese peanut butter cup represents the apothecium. The fruiting body is the sexual reproduction structure. The spores are produced in the asci (plural) represented by the sesame seeds. Next the tortilla layer is the upper cortex/thallus/skin. The green beans represents the algae. Fourth, the rice noodles are the medulla (hypha) layer. Lower cortex is another tortilla. Finally, the chocolate plays the role of the rhizines or the holdfasts. In this case, the yummy part. LOL (Disclaimer: The food lichen idea was from a recent purchase, Common Mosses, Liverworts, and Lichens of Ohio by Robert Klips. Nice book!)
Indeed, this post was only a snack-sized introduction to lichens. Maybe you will be hungry for the full “meal” now. And that is my food for thought. 😉
What a great story – food for thought!
Thanks for the lesson and love love the robofalcon.
Fascinating and informative.
OMG your edible lichen model is the greatest! Thanks for taking the time to produce this most interesting and educational post.
Thank you all! It was a fun challenge making the food lichen. 🙂
Your lichen sandwich is great!!