|What is that weird looking stuff on the bark of my tree???
Besides photosynthesizing algae, lichen can also be comprised of fungi and cyanobacteria, formerly known as blue-green algae. These organisms take nitrogen gas out of the air and turn it into biologically usable compounds, i.e. food for the fungi and cyanobacteria. Lichen provide a winter food source for many animals, nesting material for certain flying squirrels, produce over 500 unique biochemical compounds of human interest, can be used to dye sheep wool yarns and are used as a quick and inexpensive way to determine air quality. Lichen is very sensitive to air pollution and can be used to determine amounts of air toxins. So don’t be worried about that weird looking stuff on the bark of your tree, the lichen is just holding onto the surface causing no harm. Lichen can also be found growing on rocks, soil, even metal and plastic!