Growing on Everything but Little Understood: The Strange Ecology of Lichen

Lichens are a close symbiotic relationship between fungi and alga. The fungi species are responsible for most of the lichen’s size and shape, while the alga lives on the surface of the lichen and photosynthesize, providing energy for the entire organism ( U.S. Forest Service) . Many lichen species are made up of multiple species of alga. About 3,600 species of lichens are native to North America, where they mostly grow on rocks, trees, and soil ( U.S. Forest Service) . Lichens are also excellent indicators of environmental quality since they absorb air pollutants and provide a record for pollution in an area ( Haughland  et al., 2018). The strange biology and diversity of lichens, however, make identifying species particularly difficult. Lichen datasets often contain many errors, including geographical bias and misidentified species.  To understand the current state of scientific knowledge on lichen ecology, Haughland  et al focused on the fruticose lichen species  Cladonia rei  in Alb