British soldiers, pyxie cups and old man's beard are just three
of Missouri's nearly 500 species of lichens. Lichens are unusual
life forms, because each one is a combination of two different organisms:
a fungus and an alga or algalike bacteria. There are more than 25,000
species of lichens on earth; they grow in deserts, rain forests,
on the North and South Pole (there are 350 species in Antarctica),
and even
in the ocean. Lichens can survive tough climates by drying out and
halting photosynthesis until water is again available. They grow
extremely slowly, their radius increasing at about .1 to 10 millimeters
a year. At this growth rate, some mature lichens may be several
thousand years old!
Lichens are often the first life form to colonize bare rock and,
as they decay, build soil. Lichens, especially reindeer "moss,"
provide food for wildlife. Lichens are very sensitive to pollutants
and serve as indicators of air and water pollution.
|
|
