Whats a lichen if not a plant
(Note: writing this response with Capitals™ bc its long and kind of hard to read otherwise, I’m trying to do that more with my longer posts)
Either an ecological event or a superorganism, depending on how you look at it.
To explain this. like. we do not ‘know’ what a lichen is. We know like, what they are, or at least we’re getting increasingly closer to finding out everything that makes up a lichen, but lichenologists have really struggled to define it as like, A Sole Thing. Botanists and mycologists of the past thought lichens were primarily fungi, because when you dried one out and weighed it, most of the dry weight was fungus; this is why today we still name lichens based on their fungal components, while it turns out that the give and take of all organisms in a lichen are pretty much equal.
It’s a symbiotic relationship, we’ve known that for a long time, but now we know, for instance, that some fungi can pair up with different species of algae to make different lichens. How can we reliably name something after it’s fungus if that fungus can pair up with different things to make multiple different ‘species’? And as of 2016 we know that lichens can have up to four different players: a fungus, an algae, a yeast, and (in some families) a second fungus, previously thought to be parasitic on the lichen itself.
I will personally argue that lichens are an ecological event. To me, this theory gets down to lichen reproduction, which is….completely off the shits.
Lichens can reproduce in a few different ways, the simplest ones being 1. a piece of lichen breaks off and lands in a fitting environment, creating a new lichen that’s a clone of the mother system, and/or 2. a lichen has special organs that release specially-made ‘mini lichens’ that have the main components packaged together into little ‘spores’ (these organs are called isidia and soridia, and look slightly different), creating a similar result to #1 with a clone of the mother system.
Now, you may be wondering: ‘But lichens have sexual structures. can’t they have like, Lichen Sex™?’. Which. Like. This is where it gets wild, because it ties back to the ecological mystery of how lichens ‘make new lichens from scratch’ so to speak.
The thing is, those sexual structures don’t have the components paired together. They only produce sexually-made spores of the fungus, and if these spores land in the right conditions, they won’t form a lichen, they’ll form a non-lichenized version of that fungus. So, conventionally, as we currently understand it, the way for them to form a new lichen would be for two compatible spores- one algae and one fungus, or like, one algae and one fungus or one yeast, we don’t know how those other components fit into the equation yet– to meet in the right conditions, under which case the pair recognizes each other and starts to spontaneously go down an entirely different developmental path to become a lichen. Keep in mind that lichen and algae spores are like…everywhere in the air and in the world around us, just the majority of them don’t find the proper growing conditions and die, so this does happen enough to make all the lichens we see on a day to day basis.
But. There are agonizing mysteries about this process. For example:
-We do not know how the algae and fungal spores, when they meet, know that they’re compatible in the first place. Like, on a cellular level.
-We do know that after a certain point, the organisms involved are locked into their developmental path. They need to meet at an extremely young age (as spores) to become a lichen. If a mature fungus and a mature algae meet, nothing happens, even if they would have been compatible as spores.
-Science, to my knowledge, still has not yet been able to replicate the ‘lichens being made from scratch’ process in a lab. The spores will recognize each other and start developing on a microscopic level, and then they’ll just….stop developing and die, which is why we can only produce new lichens in a lab by growing sterilized fragments from old lichens. Whether or not we’ve just been like, missing all the ‘ingredients’ and you need a yeast or second fungus or something to finish the process, I have no idea.
In conclusion: Lichens are mysterious soups. Lichens, to me, aren’t a thing that lives, but more like a thing that happens between living things. It’s an event of several different things coming together to proliferate on a tree or a rock or wherever, and they are everywhere, and we do not know everything about what they are or how they work. Some people, again, will call them ‘superorganisms’, which isn’t wrong either, but I personally like to think about them in a weird like…..temporal sense? Idk man they haunt me every day of my life.
