|Spalted wood, rusty nail, lichens and melting snow.|
|A leaf lichen with an unusual centre, sort of like a tiny, green cauliflower.|
|Lichen "leaves" are like snowflakes; no two alike.|
|Lichen, snow, and a budding branch.|
Wikipedia has a long article on lichens. Some interesting tidbits:
Lifespan is difficult to measure because the definition of what constitutes the "same" individual lichen is not precise: ... lichens grow by vegetatively having a piece break off, which may or may not be considered to be the "same" lichen; moreover, two lichens can grow into each other and then become the "same" lichen.
The European Space Agency has discovered that lichens can survive unprotected in space. ... two species of lichen ... were sealed in a capsule and launched on a Russian Soyuz rocket .... Once in orbit, the capsules were opened and the lichens were directly exposed to the vacuum of space with its widely fluctuating temperatures and cosmic radiation. After 15 days, the lichens were brought back to earth and were found to be in full health with no discernible damage from their time in orbit.
(No wonder they don't mind bare cliffs!)
They can even live inside solid rock, growing between the grains, and in the soil as part of a biological soil crust in arid habitats such as deserts. Some lichens do not grow on anything, living out their lives blowing about the environment.
Most poisonous lichens are yellow.
In the past Iceland moss ... was an important human food in northern Europe, and was cooked as a bread, porridge, pudding, soup, or salad. Wila ... was an important food in parts of North America, where it was usually pitcooked. Northern peoples in North America and Siberia traditionally eat the partially digested reindeer lichen ... after they remove it from the rumen of caribou or reindeer that have been killed.
|Microscopic lichen growing on concrete dust. Square: 1.7 mm. Photo: Bob Blaylock.|
Lichens confuse me, and the more I read, the more confused I get. But they're fascinating, so varied and so inventive; worth the effort to try to make sense of them.