Not long ago, I spent a glorious sunny day wandering around Cass Field Station while my husband met with some students there. It was nice to take a solo walk and go at my own pace, stopping at whatever plants, bugs or rocks caught my fancy.
Once nice find was this beautiful lichen, Rhizocarpon geographicum.
Lichens are strange organisms comprised of an alga living within a fungus. The alga provides food through photosynthesis and the fungus provides protection and nutrients for the alga.
R. geographicum is an alpine/subalpine lichen and, like many lichens, is sensitive to air pollution, thriving only where the air is clean. It is not, however, a fragile organism.
In 2005, R. geographicum was one of two lichens launched into space. The lichens were exposed to 14.6 days of open space—vacuum, wide temperature fluctuations, intense UV light and cosmic radiation. Upon return, R. geographicum showed little harm from the experience.
Not only is R. geographicum tough, some individuals in the Arctic are estimated to be 8,600 years old, making them the oldest living organisms on Earth. Their longevity and predictable growth rate make them useful tools for determining when glaciers retreated from an area.
But I didn’t know all this about R. geographicum when I found it on the rocks at Cass. I simply admired its beautiful mottled colours and soft texture.