are there any edible lichens? not necessarily lichens that are eaten, just ones that could be
Very few, but yes! Lichens are hardly ever a preferred food source (they resist cultivation, are slow growing, labor intensive to prepare, not easily digested by the human body, and don't taste great) but are sometimes used as thickeners, flavoring agents, traditional medicines, or as a back-up food source in times of famine. A few of note:
Cetraria islandica, aka Iceland moss, fjallagrasa
The only lichen I have really eaten! It is used as a flavor additive, tea, and cough medicine (the efficacy of which is debatable), and is made into alcohol becuase people will make anything into alcohol. I have had traditional Icelandic flatbread made with C. islandica, and regularly drink C. islandica schnaps:
It has a grassy, earthy, kind of musky, tanic flavor. It's an acquired taste, to say the least. But it's grown on me.
Bryoria fremontii, aka Wila, edible horsehair lichen
This lichen is incredibly culturally significant to the First Nations people of western North America, and has historically been used as food, medicine, bandage material, building material, diapers, dyes, fiber, and much more! Traditional Salish food preparation involves cleaning, soaking, and baking the lichen in an underground pit oven, the whole process taking several days to form dense, almost gelatinous loaves.
Be warned, however, if this has you thinking about going out and eating some right now: certain chemotypes with a yellow tinge contain toxic vulpinic acid, which is bad for you.
Parmotrema sp., aka, black stone flower, kalpasi, dagad phool
Lichens of this genus from eastern Asia are used as an aromatic spice and thickening agent in some parts of India, and are often hailed for their medicinal properties.
I had a jar of homemade curry spice gifted to me that used it, but can't say that I could really distinguish it from all the other spices.
Circinaria sp., aka manna or heavenly bread
You may have heard how god blessed the Israelites wandering in the desert with "manna from heaven" to stave off their hunger, and there is some ethnobotanical evidence that this was referring to vagrant Circinaria/Aspicilia lichens. It makes some sense: when dry, the lichen is pale and small, and difficult to distinguish from the arid dirt of its preferred habitat, but after rain, it swells and darkens in color, and looks as if it just fell out of the sky! The evidence is let's say, dubious, but it is fun to think about.
This is by no means an exhaustive list--just a few I have looked into. If anyone else has experience with edible lichens, feel free to add on!
Sources and further readings:
Edible wild plant use in the Faroe Islands and Iceland
Ethnolichenology of Bryoria fremontii: Wisdom of elders, population ecology, and nutritional chemistry
Diyarbakir's heavenly bread and other manna of things
Kalpasi: The Black Stone Flower spice of Southern India
Ethnolichenology—The Use of Lichens in the Himalayas and Southwestern Parts of China
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