Cladonia stellaris, the “Star-tipped Reindeer Lichen,” was selected by Canadians to be a national lichen species in a vote held in 2020. (Photo credit: Anders Wahl. Obtained from Wikimedia Commons.)
While Canadians might first choose the moose or the beaver to represent Canada, we need not look further than the ground on which we tread to find a worthy candidate offered by nature.
Because Canadians have the reputation for being good, kind-hearted people, it is only fitting that Canada is highly populated by lichens, little-known composite organisms that spread their goodwill and exist because of the mutually beneficial relationships they provide.
There could not be a better symbol on our soil because lichens benefit the environment, feed wildlife, aid in monitoring pollution, and exist - first and foremost - as an example of mutual aid.
Last year, when Canadians were given the chance to select a national lichen, of the seven species options provided by lichenologists, voters chose the “Star-tipped Reindeer Lichen” (Cladonia stellaris). Found throughout Canada, it resembles cauliflower in appearance.
The lichen organism is neither moss nor plant, although it has been misrepresented as being both. No, the lichen is a species all its own and there are approximately 15,000 kinds of lichen worldwide, including 2,500 that call Canada home.
A lichen (pronounced ‘liken’) is formed when a fungus combines with an alga or cyanobacterium. Together they create a symbiotic relationship - one beneficial to both organisms.
In true symbiotic fashion, the lichen thrives because its composite fungus and alga serve to support one another. Fungi lack chlorophyll, so they can’t photosynthesize, leaving them unable to obtain energy, and thus a source of nourishment, from the sun. Conversely, algae and cyanobacteria can photosynthesize, allowing the fungi associated with them to have a constant food source in addition to food lichens obtained from the air, minerals, and rainfall. In return, fungi provide their partner algae or cyanobacteria with a safe environment in which to thrive as well as provide important protection from ultraviolet (UV) light.
Growing ubiquitously and happily in environments from dry deserts to artic tundra,lichens are resilient. They are found on mountaintops and on the branches of spruce and fir trees. Lichens cover boulders, the tree trunks of elms and maples, and coastal rocks. They even grow on residential driveways. Lichens come in many shapes and sizes and from moss to branch-like in appearance. Because of their inherent symbiosis, they also take on the various colours of the algae or cyanobacteria with which they are partnered and can be anywhere from grey to brightly coloured.
As for their usefulness to others, lichens make up the greater part of the winter diet of caribou because lichens can survive in colder climates where other food sources are not available. They also provide shelter and camouflage for smaller animals. Once more, the sponge-like nature of lichens allows them to absorb pollutants, making them good indicators of pollution and, through lichen biomonitoring, pollutants extracted from lichen can provide us with a picture of atmospheric pollutant levels and inform us about population and environmental pollutant risk.
Even after they die, the likable lichens continue to help other species survive. While most organisms can’t make direct use of nitrogen from the atmosphere, lichens can. When lichens die and decay, they fix nitrogen in the soil, making it available for use by surrounding plants. Lichens are also among the first organisms to colonize barren surfaces, preparing sites for later plant growth by trapping moisture and windblown organic debris and then contributing to organic deposits even when they die and decay.
With a new-found understanding of their ubiquity, anyone learning of lichens might try to be more cautious of where they step while walking a trail or even around their own yard. However, lichens also (surprisingly) can benefit from being trampled upon and being carried off, “hitch-hiking” to new places where they can reproduce, spread and continue to be useful.
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By: Natalie Workewych
Natalie is a PhD Student studying Pharmacology at the University of Toronto. Her academic background includes an undergraduate degree in Biochemistry and Pharmacology. She hopes to encourage ideas through writing, and bring thoughts on science to anyone the least bit curious.
