Difference between moss and lichens
Published 7:25 pm Saturday, January 12, 2019
By Terry Rector
I think one of the neatest things is to slow drive gravel roads at night this time of year to see moss and lichens growing on tree trunks and road banks.
Daylight, traffic and spring growth just don’t do justice to moss and lichens that are out there year round. Headlights and a shortage of other greenery bring them front and center in winter.
Around here, true moss is the green fuzzy stuff growing on the shady side of trees, on roadside dirt, brick sidewalks and flat on the ground in heavy shade.
The stuff we call Spanish moss is not a moss at all. It is a type of bromeliad. Much further north a favorite common name misnomer is Reindeer moss. It’s not a moss either. It’s a group of lichen species that make up a big part of the diets of caribou, also commonly called reindeer. Remember, plant and animal common names are local and unofficial.
The biggest difference between mosses and lichens is mosses really are plants and lichens are not.
Mosses take in air and water and minerals to utilize photosynthesis to make their food for growth and reproduction. Being plants, mosses have vascular structures to move food and water within. But they do not have roots, rather merely tiny string-like structures that anchor them.
Water and nutrients for mosses come from the air surrounding them, which is the same way bromeliads get theirs. That’s why mosses are found in damp areas. They would dry out quickly in full sun.
Mosses do not bloom or produce seeds. They do have separate gender structures necessary for the production of spores instead of seeds. Occasionally moss will regenerate when a piece breaks off and falls to the right spot to take hold and live on.
Lichens, the non-plants, are like moss in two ways. There are thousands of species of each and both have a wide range of hosts.
A lichen is actually two things growing together; a fungus and an algae. Lichens are in no way mushrooms that are reproductive structures of just fungi. In the case of lichens, it is the algae that makes the food for both species. Most lichens are flat and often crusty.
Practically all our local tree species host bark lichens but the lichens are not a health threat to trees. Granted, tree limbs that are covered up in the fuzziest types and the green “mossy-looking” types of lichens are dying. But that’s because those lichens grow prolifically on dying and dead limbs. The lichens merely found the sick tree. They didn’t make it sick.
In my experience diagnosing tree ailments, it was sickly plum trees that grew the biggest variety of colorful lichens. Usually the trees were dying from root problems, but “that ol’ gray fuzzy stuff” on the limbs meant chainsaw time.
Likewise, when I looked at moss taking over a lawn beneath big trees, the moist ground environment caused by poor internal soil drainage and shade was prime for a moss species.
Terry Rector is spokesman for the Warren County Soil and Water Conservation District.