Fluorescent Lichens: Dazzling Creatures of Light

One of the great things about traveling in far northern Ontario this July was the fact that our multi-disciplinary botany team included a lichenologist.

It was great because lichens are amazing, because lichen experts are very rare, and because there’s so much left to learn in lichenology that every lichen outing seems to result in spectacular discoveries.

Lichen growing taller than the moss around it.

Powdered funnel lichen (Cladonia cenotea)—Just like in this photo, the specimen of powdered funnel lichen that we collected for exhibition at the museum is mixed with the common boreal feathermoss called big red stem (Pleurozium schreberi). Image: R. Troy McMullin © R. Troy McMullin

It was also great timing, because we’ve been making the (already ultra-cool) temporary exhibition Creatures of Light even better by adding material from the Museum of Nature’s research and collections… and as it turns out, some lichens are dazzling creatures of light.

Dr. R. Troy McMullin of the University of Guelph generously collaborated with me in finding specimens to share with museum visitors (I’ll also be adding specimens to the museum’s collections).

Lichens aren’t bioluminescent, which is to say that if you turn out the lights, they won’t glow in the dark. Under ultraviolet light, however, many of them fluoresce, glowing vividly in ways that most humans can’t detect in normal daylight conditions.

Collage: A section of lichen-covered branch under white light and the same branch under UV light, showing the lichen fluorescing.

A new exhibit—Visitors to Creatures of Light can make the lichen (Ochrolechia arborea) on this branch fluoresce by turning on the ultraviolet light. Top photo: UV light; bottom: white light. Images: Jennifer Doubt © Canadian Museum of Nature

Sometimes the colours of fluorescing lichens under UV light (also called black light) appear completely different from what appears to dominate under ordinary white light. This means, for example, that a bone-white lichen may appear a startling egg-yolk yellow under black light.

Intriguingly, scientists have not yet determined why only some lichen species contain fluorescent chemicals. They have determined, however, that they are natural by-products of the lichens’ daily life.

I have to admit that although I’ve known for decades that black lights are standard equipment in lichen identification labs, I didn’t realize how common it is to encounter fluorescent lichens in Canada. Their almost flamboyant glow makes them seem like they should be more exotic.

A patch of lichen on a rock.

Candy lichen (Icmadophila ericetorum)—Candy lichen is a favourite of many naturalists because it’s easy to recognize, with its pink fruiting bodies on a mint green crust, and its memorable alternate common name of fairy puke. Under UV light, it fluoresces because of the presence of thamnolic and perlatolic acids. Image: R. Troy McMullin © R. Troy McMullin

In the Hudson’s Bay Lowlands, however, Dr. McMullin routinely pointed out clumps of lichen for prospective display. Of one ubiquitous, brownish, stick-like specimen, he commented, “This one glows blinding blue”.

Blinding blue?! And it’s growing in every Canadian province and territory? How come no-one tells us these things in school?

Collage: A specimen of powdered funnel lichen (Cladonia cenotea) and big red stem moss (Pleurozium schreberi) under white light and under UV light, showing the lichen fluorescing.

The blue surprise—I collected this specimen to exhibit in the museum. Under UV light (At left), the “blinding blue” of the powdered funnel lichen contrasts strikingly with its non-fluorescent neighbour, big red stem moss. At right: white light. Images: Jennifer Doubt © Canadian Museum of Nature

When I wondered aloud what it might be like to turn a northern bog psychedelic with UV floodlights, Dr. McMullin referred me to another lichenologist, Dr. Robert Lücking, and the astonishing photo that resulted when he set up his black light next to a lichen-encrusted tree trunk. Dr. Lücking graciously shared that photo, and one of the same tree under white light, which you can see here.

Collage: A section of lichen-covered tree trunk under white light and the same tree trunk under UV light, showing the lichens fluorescing in different colours.

The astonishing example—Matching images (white light, UV light) of a lichen-covered tree trunk, as captured by Dr. Robert Lücking at Las Cruces Biological Station in Costa Rica. Image: Robert Lücking © Robert Lücking

As another group of lichenologists introduced them, “Lichens… belong to an elite group of survivalist organisms…”. They are tough, beautiful, unique, and puzzling. And far from being confined to remote northern peatlands, they also grow in back yards, on concrete steps and on city tree trunks, not to mention parks and natural areas—every terrestrial environment, except for the most heavily polluted regions of our planet.

A man wearing bug netting holds a hat that contains a lichen specimen.

Dr. R. Troy McMullin—Hermetically sealed against blackflies and excited to visit lichen-encrusted peatland habitats, Dr. McMullin takes advantage of all available containers for collecting lichen samples. Image: Jennifer Doubt © Canadian Museum of Nature

The real mystery is why so few people know about them. If you want to see them, step outside. If you want to see them fluoresce, stop by Creatures of Light at the museum, any time before November 9, 2014.

Jennifer covered a lot of ground on this collecting trip. Read her previous article, Blackflies, Begone! Studying the Plants of Northern Ontario’s Peatlands.

This entry was posted in Arctic, Exhibitions, Fieldwork, Plants and Algae, Tools of the trade and tagged , . Bookmark the permalink.

4 Responses to Fluorescent Lichens: Dazzling Creatures of Light

  1. Pingback: Things to know about lichens | Curious Needleworks

  2. Tim says:

    I would have to disagree that there are no lichens that glow in the dark! I have seen them many times,at one time my science teacher identified it as a glow in the dark lichens, White lichens growing flat on a dead branch that had a greenish glow at night in the woods. if you would like I am sure i can find some for you!

  3. Max Catterwell says:

    Fascinating article Jennifer thank you! There appears to be very little info on this subject and my browser found yours first!

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