What exactly IS a lichen?? Pls im just an artist who only knows that plants are pretty
oh man ive been meaning to do a full crash course on lichens for a long time but in super short terminology, lichens (pronounced like-ins) are the weird multicolored blotches you see on trees that aren’t mosses. you probably see them every day, and they exist on every continent in the world, in nearly every ecological niche, and can live on nearly any solid substrate. they aren’t plants or fungi, but are a ‘superorganism’ comprised of different algae and fungi species (and some other components science doesn’t fully understand yet, including yeasts and bacteria in some species) adapted for the relationship, so at the most basic level, the algae photosynthesizes in return for shelter from the fungal structure, and the fungal structure gets food from the algae’s photosynthesis so long as it provides shelter. to give an idea of how everything is put together in this, lichens are generally organized in ‘layers’, so if you cut a little lobe off one and look at it under a microscope, you usually can see something like this:
note that lichens have different growth forms and are overall incredibly diverse organisms, so this one is a cross section of the ‘foliose’ growth form where the lichen isn’t 100% all connected flush to the substrate, but also isn’t having a wild time going everywhere. anyway, you can see diagrams and descriptions of cross sections of all the different lichen growth forms here, if you’re interested. in general, though, lichens have a layer of fungi, a layer of algae, and another layer of fungi.
lichen reproduction is….dicey as hell tbh, and we don’t fully understand it still, but lichens don’t really reproduce as one single organism. i’ve gone further into on this blog before (my ‘lichens’ tag is….pretty diverse with all that from over the years) what’s important to know in terms of like, knowing what you’re looking at when you look at one is that the fungal component usually reproduces by means of organs called ‘apothecia’, which produce spores that are dispersed by rain, wind, or water. when you see little disk things on lichens that look like this (Xanthoria parietina):
or this (not disks, but the same thing; species is Graphis scripta):
or– and i get lots of submissions from people wondering about these when they see them –even this (these ‘cup’ fruiting structures are common in the lichen genus Cladonia, and aren’t always strangely tiered like this, but this one is Cladonia verticillata specifically; notice the little red dots around the edges of each cup, those are technically the actual apothecia):
…those….are the sexy bits. a good rule of thumb for lichens is that if something is poking out from the top, and it doesn’t look like a lobe of the actual lichen body, it’s….usually a sexy bit of one kind or another, although whether said appendage is actually producing sexually recombined things or just shedding clones of itself can vary. like, lots of stuff is going on with lichens, but apothecia are probably the most common sexy bit you’ll encounter.
anyway. that’s a very short layman’s guide to walking around in the world and seeing The Lads. @lichenaday has a good assortment of Dudes™ for your viewing pleasure, as does the national consortium of north american lichen herbaria. endless entertainment here, let me tell you
