Not everyone knows what lichen is, but Troy McMullin wants Canadians to know how lucky we are to have a lot of the fungus-based organisms.

That's why he says it's time for the country to officially pick a national lichen species.

McMullin is a research scientist with the Canadian Museum of Nature. He specializes in lichenology and is asking Canadians to vote for one of seven lichens on the museum's website to determine Canada's national species.

"In Canada, it's quite possible we have the highest abundance of lichen in the world — yet most people don't know what a lichen is," McMullin told As It Happens host Carol Off. "They're very ecologically important."

After drafting a criteria and consulting with scientists across the country, McMullin narrowed the nominations to seven lichen eligible for the national vote: Boreal oakmoss, common freckle pelt, concentric ring, elegant sunburst, horsehair, star-tipped reindeer or yellow map.

"They are small, but they are spectacular," McMullin said. "They're colourful, they come in a wide range of shapes and sizes and they're everywhere in Canada."

The Boreal Oakmoss is one of seven lichen nominated to be designated Canada's National Lichen. (Troy McMullin)

To be fair, McMullin says it's hard to classify lichens and they often get lumped into other categories of organisms that cling to rocks and trees, like moss or fungi.

"It doesn't fit well into the ecological boxes that we've created in what a species is because it's actually multiple species working together," McMullin said.

"The bulk of it is a fungus. It's a fungus that has somewhat transformed into a greenhouse where it's growing and farming algae and cyanobacteria."

McMullin says it's because of this unusual union that lichen is actually recognized as its own species or organism.

Troy McMullin is asking Canadians to vote for a national lichen. (Paul Sokoloff)

For those who might vote with their stomaches, a word of warning. Some lichen may be eye-catching and look appetizing, but McMullin says most wouldn't be very palatable to humans.

"They are sponges, so if you're anywhere near a city or a pollution source, they take in any kind of air pollution that's around them," McMullin said. "So it wouldn't be wise to eat them around cities."

But it's a different story for animals, many of which rely on lichen to survive in colder climates.

"Lichens don't change throughout the year," McMullin said. "So in the winter, as a food source for animals, they're available."

McMullin says the Elegant Sunburst lichen grows on rocks that birds like to perch on and "it really likes the nitrogen left behind by the birds." (Troy McMullin)

Looking over the short list, McMullin admits each lichen is worthy of the national title.

"They are spectacular and they're unusual and very bright and showy," McMullin said.

Each has its own unique character and genetic make-up. For example, there's the bright orange elegant sunburst, which McMullin says grows across Canada.

"It's really an eye-catching species," McMullin said. "It grows on rocks that birds like to perch on. It really likes the nitrogen left behind by the birds."

Another strong contender is the common freckle pelt, which McMullin says is commonly found in the boreal forest.

"It really looks just like leafy lobes growing on the ground," McMullin said. "The special thing about that one is that usually there's only one photosynthesizing partner within a lichen, and that's an algae or a cyanobacteria. But that species has both."

Usually there's only one photosynthesizing partner within a lichen — either an algae or a cyanobacteria. But McMullin says the Common Freckle Pelt has both. (Troy McMullin)

McMullin knows that even with something as tame as lichen, it will be difficult to get such a big country to agree on one national species.

He remembers the drama that unfolded during the national bird debate when the loon and grey jay split the country apart.

"There's all kinds of feedback already saying, 'Why wasn't, you know, British soldier included? Or, why wasn't old man's beard included?'" McMullin said.

"That's part of the fun of it. We wanted to get it out there for people to discuss, to put lichens on the map and give them their due. Just because they're smaller than most organisms, they're still really important."

Once the public has had their say, McMullin and his team will submit the winning species to the Canadian Heritage office to consider formally designating it as the national species.

The polls close on March 20.

Written by Sarah Jackson and John McGill. Produced by Sarah Jackson.