Then we visited one of my favorite areas of France, the Bouriane, where people with respiratory problems actually go to breathe in the pure air. The woods, gardens and even fruit trees drip with lichen. It was there I learned that lichen is Mother Nature's clean air indicator. (This is why I love gardening so much- there is always something new to learn.) Without getting too technical, lichens are actually fungi living in a symbiotic relationship with algae. Although they do not need much in the way of moisture and nutrients, growing in barren places such as the tundra and on desert rocks, they do obtain the meager nutrients they need generally from rain water. If that rain water has pollutants, there is no lichen. There have been many studies throughout the world, including a study of our own National Forest Service, showing the purer the air, the greater the density of lichens, with very little growing in city environments, as you might expect. Sulfur dioxide, a product of fuel combustion, nitrogen dioxide, fluoride, ozone, and especially acid rain when absorbed by lichen, destroys it.
So, from that time on, no more scraping of lichens off my trees. I let them wear their lichen like badges well earned. The lichen has multiplied, even covering the wood and stone benches along the woodland paths. The patterns and designs and multi-gray and verdis gris colors are fascinating.
The strange thing is that when we first started our project of rebuilding these 18th Century houses on an empty field, I do not remember seeing any lichen on the perimeter trees. Instead of turning an agricultural field into a series of suburban houses and lawns, we kept most of our field intact, encouraging the buttercups and wildflowers, at the same time adding trees, trees, and more trees, my passion, nestling courtyard gardens and lily ponds around the houses, restoring the pond and keeping the lawn to a minimum. Whatever we did, the greenery filters the air and our lichens are happy. They drink up healthier and we breathe healthier - another great symbiotic relationship.