Naturalist Fact: Lichens

crustlichen

Crustose lichen commonly found on Southern Magnolia trees on LSSI.

folioselichen

Foliose lichen on a Southern Red Cedar.

frutioselichen

Fruticose lichen on a downed oak branch.

 

Lichens can be found in several habitats across Little St. Simons Island, and they take a variety of forms and colors. Lichens have the ability to survive long dry periods, but after a good soaking rain, they will catch your eye with their bright colors and interesting textures.

Lichens are actually not a plant, but a composite of fungi and a photobiont that behave together as a single organism. The fungus usually provides the structure and facilitates the uptake of water and minerals, while the photobiont generates sugars through photosynthesis. The photobiont is usually a green algae, but can also be a cyanobacteria.  In most cases, the fungus and its photobiont would not exist outside of the lichen association.

Lichens have the ability to grow on soil-less surfaces, and therefore are one of the first colonizers in many plant communities. They are very slow-growing, but can derive most of their water and nutrients from the air and rainfall. On Little St. Simons Island, you can find lichens growing on the smooth bark of Southern Magnolias or Southern Red Cedars. You will also find it colonizing open sandy areas.

Lichens can be divided into three groups based on their morphology. Crustose lichens grow flat against hard surfaces (like a crust), and are the simplest form of lichen. As they grow, they radiate out from the center, so the newest growth is on the perimeter. Foliose lichens grow in a more “leafy” structure, but stay close to the surface they inhabit. Fruticose lichens are more shrub-like, growing on a stalk or exhibiting a highly branching, more complicated structure. On Little St. Simons, you can find lichens that belong to all three of these groups.

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