Tuesday, February 21, 2023

Lichen or Not?

By Mark Bower
Recently, while walking behind Bob and Barbara Kipfer’s Bull Creek abode, I (almost literally) stumbled across a log which was partially covered by what looked like green slime with little fungi growing from it:
Interestingly, the fungi were only located on the green areas. It turns out that these little white fungi are Multiclavula mucida, with the unwieldy common name White Green-Algae Coral Mushroom. It has an obligate association with a green algae of the Coccomyxa genus. The algae are encapsulated by the fungal hyphae. While the algae aren’t incorporated into the body of the fungus, the association is not unlike that of more typical lichens. For that matter, this fungus-photobiont relationship is very similar in function to the mycorrhizal relationship between plants and fungi. So is this a lichen? Functionally, it is. Structurally, it is not.
A lichen represents an association of a mycobiont (fungus) and a photobiont (algae and/or cyanobacteria). In combination, these organisms form a unique structure. Separately, they usually are incapable of surviving. 
Typically, the fungal component of a lichen will incorporate one or more photobionts into its body. The photobiont provides photosynthetic products along with some vitamins to the fungus. In return, the algae receive a moist, protected place to live.

Cross section of a layer of algae just under the surface (cortex) of the fungus.

Editors note:

In most relationships including lichens, there is a fine line between a parasitic and symbiotic relationship. 

Symbiosis is defined as an "interaction between two different organisms living in close physical association, typically to the advantage of both."  As described above, the fungus provides the structure (home?) where the algae lives, paying the fungus "rent" in the form of photosynthetic energy.

In our home, the kitchen provides the energy for maintenance of the home.  While the balance varies from day to day, the photobiont is in the kitchen for several hours while the mycobiont is in the family room writing this blog.  She will soon be in here editing my writing.  Am I a parasite?  Don't answer that!


Wanting more information on lichens?  Here is a good place to start from the US Forest Service.