All of the world's animals, plants, fungi and microbes are connected. Being curious about nature can inspire you to explore the wonders of the natural world. Have you ever taken a close look at lichen? Lichens are all around us and are mostly ignored. But if you tune in to your surroundings, perhaps you will begin to become aware of lichens on rocks, tree bark, soil, gravestones, wood benches, roofs, or fences. Lichens can also grow on glass, metal, plastic and cloth. Lichens are living organisms. Although it looks like a plant, it’s not. In order to survive, lichens need water, light, air, nutrients, and a surface on which it can grow. They get water from rain and fog, and absorb water vapor from the air.
What are lichens?
Until the use of microscopes revealed otherwise, lichens were once classified as single organisms. Magnification showed lichens were two organisms living together in symbiosis: a fungus and an algae. The word symbiosis was invented to describe lichen. The fungus provides support, water, and minerals for the algae, while the algae photosynthesizes, producing food for the fungus.
In recent studies it has become evident that while lichens contain at least two different kinds of life made up of organisms belonging to different kingdoms, they are also ecosystems for many other microorganisms, such as bacteria, yeast, and additional algae and fungi. Lichens are now understood as a community of organisms rather than a simple fungi-algae association.
Appearance:
Lichens come in different forms, colors, and sizes.
There are four main lichen body types: crustose (crusty), fruticose (shrubby), foliose (leafy), and squamulose (scaly).
Lichens can range in color from grey, green, black, white, yellow, orange or red, and almost everything in between. Individual lichens often form mosaics of color.
When dry, lichens appear dull-colored, the color of the fungus. But when wet they are completely transformed when the colors of the algae layers shine like superstars.
Lichens range in size from as small as a shirt button to strands that can be several feet in length.
Lichen habitat:
Lichens are everywhere throughout the world. They are the dominant form of life on about 8 percent of the earth’s surface. Lichens grow in temperate, tropical, and polar regions. They survive in some of the most extreme environments on earth: arctic tundra, high mountain peaks, deserts, and rocky coasts. Lichens can survive a complete loss of water, become dormant, and then rehydrate when water becomes available. To ensure survival, “Lichens produce an arsenal of more than 500 unique biochemical compounds that serve to control light exposure, repel herbivores, kill attacking microbes, and discourage competition from plants," according to the Lichens of North America site.
Uses:
Lichens provide forage, shelter, and building materials for deer and other large animals, as well as birds, rodents, and insects, as described by the USDA Forest Service.
Lichens are used in deodorant, toothpaste, ointments, extracts, perfumes, and dyes for fabric. Some species of lichens are also thought to have medicinal properties.
Are lichens on trees harmful?
Tree-dwelling lichens are not harmful to trees. They are often mistaken for destructive fungi or diseases, but they are not pathogens or parasites, and do not cause disease. Lichens attach to trees but do not feed off the bark. They produce their own food using sunlight energy (photosynthesis).
On a final note, lichens are a partnership between organisms unlike any other organism on earth. They are all around us and we hardly notice them.