The lichen is typically light gray in color and may have disc-shaped fruiting bodies.
Mosses and lichens are often confused, in part because many common names for lichens include the word “moss.” In fact, the two agencies are radically different and not even in the same field. Both are fascinating organisms, often overlooked because they are small and not very showy. They grow throughout the world and are used for dyes, animal fodder, ornamentation, medicines, and religious practices.
Moss on the rocks around a waterfall.
Lichens are perhaps the most amazing living things on Earth because they represent a symbiotic relationship between a fungus and algae or cyanobacteria. The symbiotic nature of lichens was not fully understood until the 19th century, when the idea was first proposed. They form a fascinating example of cooperative relationships in nature, with the fungus using the algae or bacteria for energy, while the algae or bacteria enjoy the protection provided by the fungus.
A layer of moss.
These organisms reproduce in a variety of ways. Many produce spores that attempt to capture associated algae or bacteria, while others reproduce via fragments of lichens that break off and spread. They can grow almost anywhere in the world, from extremely acidic soils to frigid arctic conditions, and are found growing on trees, rocks, and everything in between. Contrary to popular belief, lichens that colonize trees, such as members of the Usnia family, are not harmful to their hosts and, in fact, often capture valuable nutrients.
A microscope is often needed to tell the difference between lichen and moss.
Lichens take three forms. Crusty lichens, often found growing on rocks, are characterized by a crusty appearance. They are often colored and create the bright streaks seen on rocks in the distance. Leafy lichens are leafy or fibrous and often grow on the ground or around trees. Fruit lichens form stems, which sometimes form shiny fruiting bodies.
Lichens form through a symbiotic relationship between algae and fungi.
Most observers are unaware of the ubiquitous little lichen, but a determined investigator can find hundreds of species in a short walk in any region, from the depths of the forest to the streets of a large urban area. They can be extremely difficult to identify properly, often requiring the use of a microscope and specialized staining to uncover the fused identities that come together to form the lichen.
Moss, on the other hand, is a plant. It belongs to the bryophyte division, which is one of the most genetically diverse divisions on Earth, including 10,000 species in 700 genera. These organisms can also be found throughout the world and form an important part of many ecologies, preventing erosion, retaining water, and feeding many species of animals and insects. Moss is an archaic non-vascular plant, which means that it has existed in various forms for millions of years and reproduces by expelling spores. Like lichens, it can also reproduce from broken parts of the mother plant.
Physically, these two organisms can be difficult to distinguish. In general, mosses are green, grow in dark, moist areas, and have small leaf-like structures in addition to stems. Lichens often have a gray or white appearance, and many also create disc-shaped fruiting bodies.