The Amazing World of Lichens

This week’s blog was written by Sierra R., a Bass alumni. This summer Sierra returned to the Wildlife Leadership academy as an Assistant Team Leader to continue to learn about the environment and the many career fields available. Sierra’s hobbies include hiking, nature journaling, Girl Scouts, and theater.

During my hikes in the woods, I have seen many different forms of life ranging from plants to animals to fungi. Yet there’s one common organism I have not given much thought about. That organism is lichen. You have probably all seen lichens somewhere outside. They often grow on trees, rocks, and sides of buildings. In fact, lichens are one of the most widely spread and adaptable organisms on the planet. Their habitat ranges from desert biomes to deciduous forests to cold, almost uninhabitable tundras, yet most people don’t know what lichens exactly are.

Example of a fruticose structured lichen

Lichens are not just one – but two different organisms formed together, and they are truly one of a kind. Lichens are the product of a mutual partnership between algae and fungi. In an interesting twist, both of these organisms are grouped outside of the plant kingdom. This means that lichen is not part of the plant family at all, but technically the fungi family. Algae is part of the kingdom Protista, while fungi are in a kingdom entirely of their own (the Fungi kingdom). In lichen, fungi give algae a structure to grow with; Together, their cells form different layers to create lichen. The fungi provide algae protection from harsh environments. Algae usually only thrive in water-based environments, but the fungi provide enough protection so that algae can live and grow in land-based ecosystems as well. The algae, in turn, perform photosynthesis, which makes energy for both the algae and the fungi. This positive relationship is largely part of the reason why lichens are so widespread even in the harshest environments.

Example of a crustose structured lichen on a rock

Apart from lichens’ ability to thrive, some species also have the remarkable ability to indicate air quality. Because lichens lack a root and vascular system, they get all their water and carbon dioxide from the air. When pollutants go into their system from the air, it can affect the color and health of the lichen. Thus, healthy lichen indicates clean air. Because there are so many different forms of fungi and algae, there are a plethora of different lichen species. According to the U.S Forest Service, there are about 3,600 species of lichen in North America. Because of their variety, it can be hard to group lichen, but there is a basic system to keep them organized. There are three main types of lichen based on growth; foliose, fruticose, and crustose. The most common types that you are probably familiar with are crustose and foliose lichen. Foliose lichen is almost crust-like but not quite flat; it often looks leafy in appearance and has two sides you can discern. Crustose lichen, on the other hand, grows as a flat crust. It always has one side flattened against its growing surface. The last category is fruticose. Fruticose lichens are not flat at all. Instead, They form either self-supporting structures or thin hair-like structures.

Example of a foliose structured lichen

No matter where you are, you are bound to find some form of lichen. For such a small organic structure it is truly an amazing life form that shows the teamwork of two unlikely organisms.

The photos used in this blog belong to the author.