Have you ever wondered what those colorful crusty growths on tree trunks are? You’ll be happy to know that they are not usually harmful, but simply a relationship between three separate species that are mutually helpful to one another. The fungal part of this relationship cannot survive without the availability of photosynthetic products from the other two species, green algae and cyanobacteria.       Lichens grow on trees, shrubs, soil, and rocks and provide additional moisture and protection to whatever they grow on. If a tree or shrub [...]