Lichens have the ability to shut down, allowing them to tolerate extreme desiccation in a dormant state. They recover quickly when conditions improve, restarting photosynthesis and growth. Two lichens ...

Q. The roof on our cottage has been developing a mossy or lichen coating for the last several years. It doesn't seem to wash off easily, and I'm wondering if it is hurting the shingles. What can we do ...