Map Lichen

I tried to go downhill skiing this morning, but the lack of snow coupled with gusty winds made conditions pretty awful.  I gave up and decided to go for a walk instead.  There were only a few inches of snow on the ground near the Little Laramie River above Centennial, even though it's January in the supposedly snowy Snowy Range.  There was definitely no need for skis or snowshoes, though.  Except in a few drifted places, I didn't sink in at all.  The wind had blown some bare spots--grass was even visible at times!--and rocks were sticking out of the snow.  On numerous rocks, I noticed green map lichen, Rhizocarpon geographicum. 

During summer hikes, I often enjoy looking at the lichen growing on rocks, finding all kinds of colors and shapes.  Most rock lichens are known as crustose lichens (crust-forming) as opposed to the other kinds that grow on trees or look more like plants.  The species can be very difficult to distinguish.  I try to avoid walking on lichen-covered rocks, because lichen only grow very slowly on undisturbed areas.  They also do not do well in polluted air, so it's nice to know that the air quality of the Snowies is still very good.

The site wisegeek.com describes lichen as a symbiotic relationship between fungus and either algae or cyanobacteria.  "Lichen is a kind of primitive plant species that's nothing more than strands of alga linked with roots and branches of a fungus that together absorb minerals from the ground and conduct photosynthesis." 

I found this relationship further explained at ohioline.osu.edu:  "The alga or the cyanobacterium (the photobionts) produce carbohydrates through photosynthesis which then serve as food for the fungus. The fungus, in its turn, provides a steady supply of moisture to the photobiont, provides a substrate helpful in providing the right amount of light to the photobiont, and protects this alga or cyanobacterium photobiont within the fungal tissues. There are many variations of this relationship...bottom line, as the great lichenologist Trevor Goward once said: Lichens are a case of 'fungi that have discovered agriculture.'" 

Before today I had never really thought about lichen in winter, because they were usually buried beneath feet of snow.  They generally tolerate the severe cold just fine, and further research revealed that this species of lichen can even survive in space.  Leslie Mullen for Astrobiology Magazine reports:  "The lichen were subjected to the vacuum, wide temperature fluctuations, solar ultraviolet (UV) and cosmic radiation of space for over two weeks.  Two different species of lichen flew in the Biopan [on the outer surface of a satellite] -- Rhizocarpon geographicum and Xanthoria elegan -- and they remained dormant while in space. When they returned to Earth [protected from the heat of re-entry], they exhibited no physical damage, and soon resumed their normal photosynthetic activity. Lichen are multi-cellular and eukaryotic, making them the most complex organisms to survive exposure to space conditions so far."  How's that for an amazing creature?