Lichens are virtually indestructible and grow in funky places. No place is too cold, to dry or too hot for Lichens to grow. They have even survived at minus 460 degrees F (-273 C) -- absolute zero. As an example the eye-catching orange ones you see on the picture above prefers to grow throughout the arctic on rocky surfaces and old bones that have been soiled by pikas, arctic squirrels and bird droppings!

Why? Well, small mammals and birds of course like to use rocks and anything else sticking up from the flat tundra as an outlook post -- just like they use trees further South. And of course, they like to mark their favorite post. As such over time these spots become soaked in urine which is high in nitrogen and this particular lichen finds that to be perfect for growing on such nitrogen-enriched rocks.

The Polar Inuit of Northern Greenland calls them sunain anak, meaning the sun’s excrement!

Besides growing on rocks, lichen also settle on bark, bones, discarded antlers, old, metal artifacts and even dung!

With more than a 1000 of its kind growing in  North America, Arctic Lichen is the most dominant plant of the continent. One of the oldest and toughest plants on earth, this strange hardy plant is actually the number one player in the plant world with roughly 20,000 of its kind worldwide.

But the fungus is not doing it all alone! See, you can kind of think of the lichen as a living prison cell. Inside this tough adaptable plant structure lives an algae which is kind of prisoner of the fungus -- a relationship biologists call controlled parasitism. Most lichens are three-layered organisms, with an algae layer sandwiched between two layers of fungus. The chlorophyll-rich algae produces the food (sugar) for the lichen through photosynthesis.

Image link
in courtesy of NACSE

Though it may seem as an odd way of living it apparently works great..Some arctic lichens are thousands of years old, having lived since the earliest days of human civilization. And this actually makes lichen a great tool for scientists!

Scientists use lichen to estimate when glaciers disappeared!! Lichens are colonizers, meaning they are always the first to move into new areas, and they do so fast.

As the glaciers receded, lichen would move into the terrain almost instantly and since scientist have a very good idea of HOW fast the lichens grow they can just measure the size of this colonizer and then from there figure the disappearance of glaciers -- In Canada they found some lichen that had been there for more than 5000 years!

Besides being pretty, lichen is of great importance in arctic ecosystems, being the chief winter food of reindeer, moose, and caribou. But also for humans it has turned out to be a food source -- "Arctic Salad" which you can actually eat. But remember to cook them first! If not you will probably get nausea and diarrhea as so many other explorers before you. Not because any of the species in the Arctic are poisonous, but most of them contain acids that should be boiled out. The most popular "salad" is a black leathery version growing on rocks called "rock tripe" (Umbilicaria)..As you can imagine it is not too tasty but if you are hungry enough....

Lichens are also dye sources; one called archil is used as a food-coloring agent and in chemistry to form litmus. Strips of paper impregnated with a blue or red litmus solution, are used to indicate the presence of an acid or a base in a solution; acids turn blue litmus red, and bases turn red litmus blue.

Learn ALL about lichens - in...(just click on the image)

ALL Above links (and their images) are in courtesy to NACSE - Thank you!