This spring I visited Red Butte Gardens in Salt Lake City for the first time. My favorite part was a small and very non-descript garden, tucked alongside a walkway and devoted to an organism that isn’t a plant at all, but instead a very under-appreciated genera of life – the lichen.
Lichens are those colorful crusts found growing on rocks and trees, and while sometimes plant-like in appearance, they are not plants. Lichens have no leaves, stems, roots, or vascular systems. Even more strange, lichens are not a single organism, but instead a partnership between two organisms: a fungus and an algae or cyanobacteria. Because the fungus is generally the dominant partner, lichens are classified as members of the Fungus kingdom.
The partnership exhibited by these two organisms is an example of mutualism – a relationship where both parties benefit in some way through their interaction. In this case, the fungus provides a safe and secure home for the alga or cyanobacteria, which in return photosynthesizes and provides the fungus with nutrients. Cyanobacteria and algae are typically found in water and are prone to drying when exposed to sun and wind. The fungal partner provides shade and protection from desiccation by sheltering the algae within its body. As a result, lichens are incredibly drought-resistant and can be found in a wide variety of habitats including some of the most extreme environments Earth has to offer. In fact the Rosette Lichen or Physica dubia grows in both Antarctica and the Mojave Desert!
Lichens are not just interesting from a biological perspective, but also a chemical one. Lots of lichens create and exude a suite of chemicals, the roles of which aren’t entirely known. Some are thought make the lichen distasteful to predators, while others may help block harmful UV rays and increase membrane permeability to facilitate the movement of nutrients, water, and cellular byproducts between algae and fungi.
These chemicals have also attracted the attention of scientists, as some exhibit antimicrobial, antiviral, anti-tumor, and insecticidal properties. Many are being analyzed and tested for a variety of medicinal and household uses and may soon become a key ingredient in a physician’s arsenal. Already, these organisms are utilized by humans in a number of different ways, and have been for hundreds of years.
In some native cultures around the globe, lichens are a part of the traditional diet for both people and livestock. However, most lichens have little nutritional value, are bitter tasting, and some can be toxic. Lichen extracts are also used as natural dyes for wool and cloth with colors ranging from browns and purples, to yellows and oranges. Other uses include the manufacture of perfume, cosmetics and sunscreen, a substitute for hops in brewing beer, and as a key ingredient in litmus paper.
Lichens are also sensitive to air pollution, and for that reason don’t typically grow too close to human habitation. In fact, lichens absorb pollutants into their tissues and for that reason can play an important role as an indicator species for pollution problems. As air pollution becomes more widespread, lichen species could be in danger of being lost. And because we have only scratched the surface of what these amazing organisms can do, who knows what future medicine could be lost along with it.
I could go on, as I have only scratched the surface of what these organisms can do. And in the coming years, I think we’ll hear of even more lichen-based breakthroughs in science and medicine. The next time you pass a colorful, lichen-covered rock, take a closer look at these incredible organisms and pause for a moment to wonder about the mysteries, and possible answers, that lie within.
For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.
Photos: Courtesy & © Andrea Liberatore
Text: Andrea Liberatore, Stokes Nature Center, logannature.org
Ivins, Robert Fogel (1998) Lichens are Fungi! Utah State University Herbarium. Available online at: https://herbarium.usu.edu/fungi/funfacts/lichens.htm
Center for Ecological Sciences, Indian Institute of Science. Lichen Chemistry. Sahyadri E-news. Issue 34. Formerly available online at: https://wgbis.ces.iisc.ernet.in/biodiversity/sahyadri_enews/newsletter/issue34/lichens_chemistry/lichen_chemistry.pdf See https://www.researchgate.net/publication/257213745_Sahyadri_Shilapushpa_Lichen_Chemistry [Link updated Dec 1, 2023]
US Forest Service (2013) Celebrating Wildflowers: Lichens. Available online at: https://www.fs.fed.us/wildflowers/interesting/lichens/