All about Goblin's Gold (moss)!

A fascination is born

One of my early pandemic reads was Gathering Moss by Robin Wall Kimmerer.

Apart from absolutely convincing me that mosses are wonderful and intriguing organisms with interesting human uses, I was introduced to a very unique and special species called Goblin's Gold (also known as Dragon's Gold or Luminous Moss).

The names refer to the fact that this moss 'glows'. I looked up images on Google and was convinced this was one of the coolest things evolution has ever produced.

Goblin's Gold (Schistostega pennata) in a cave.

Jymm, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via QWikimedia Commons

Sometime later, I commenced my Masters degree and managed pretty quickly to find an excuse to revive my curiosities about Goblin's Gold. We had a course project focused around creating phylogenetic trees, and we could use data on any organisms we wished.

I managed to convince 3 of my peers to do a phylogenetic tree of some mosses, starting with Schistostega pennata (Goblin Gold's scientific name) and going from there. I'll share the results of our project later on.

It soon became a goal of mine to see Goblin's Gold in real life. Luckily I was studying in areas that fall within its distribution, so I kept it in the back of my mind throughout my Masters degree.

Finally, my time comes

A couple of weekends ago I was hiking up in Sweden's High Coast. In the preceding weeks I'd gotten more serious about looking for Goblin's Gold as my time in the program was coming to an end - soon I'd go back home Down Under, outside of its range.

I was hiking "eyes down", looking beneath boulders and in little crevices, and underneath upturned tree roots.

About 200m from the carpark, I looked underneath a big, dead tree and saw the glow.

I shouted to my partner that I'd found it and I spent the next 15 minutes taking pictures and admiring it.

I had been worried that the glow wouldn't be obvious, or that you would need a torch or ambient darkness to see it properly, but it was super obvious!

The fluorescent green in these images is the glowing protenema of Goblin's Gold. The darker green is the adult.

Copyright Saphira Schroers.

I was on cloud 9 on our trip home and immediately posted the pictures to a Facebook group dedicated to mosses and underappreciated organisms.

I was thrilled to have Michael Lueth, an eminent German bryologist, agree with the ID there.

I recorded it on inaturalist, where the ID was again supported by another experienced bryologist! Check it out here: https://www.inaturalist.org/observations/121713825

So, how does it glow?

Most people's first thought is that Goblin's Gold must be 'bioluminescent' - however, this is not correct since it does not generate the light it is emitting.

In fact, Goblin's Gold appears to 'glow' simply because it is very efficient at concentrating light.

Len-shaped cells in the protonema of Goblin's Gold. Chloroplasts concentrated to one side.

Ignatov, M. & Ignatova, E. (2001). On the zoochory of Schistostega pennata (Schistostegaceae, Musci). Arctoa. 10. 83-96. 10.15298/arctoa.10.09.

The young protonema (a tendril-like thing that emerges shortly after the moss spore germinates) have specialised, lens-shaped cells and chloroplasts (the cell-organ that does the photosynthesising) that can move around the cell. These features allow it to concentrate light and maximise energy production even in low-light environments. It absorbs all the concentrated light - except green, resulting in a 'glow'.

Life cycle of mosses. See the 'protonema' stage on the right side.

Credit: Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation, Source: CK-12 Foundation, License: CC BY-NC 3.0

Adult Goblin's Gold doesn't glow in the same way.

Adult Goblin's Gold.

HermannSchachner, CC0, via Wikimedia Commons

Which brings us to: where it grows

Because Goblin's Gold is so good at concentrating light, it can persist in low-light environments where other mosses would die.

In fact, Goblin's Gold is not very good at competing with moss in bright environments, so it is only found in dark areas - typically caves and underneath upturned tree roots.

Where I found Goblin's Gold - underneath upturned tree roots.

Copyright Saphira Schroers

It has a circumboreal range occurring in North America and Eurasia.

Circumboreal range.

Nemetsy, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Is it the only glowing moss?

Actually, no!

There is a species of moss common in New Zealand which also glows.

Its scientific name is Mittenia plumula. There is not as much research about M. plumula as there is about Goblin's Gold.

Mittenia plumula of New Zealand.

Copyright © The University of Auckland, L Jensen

However, you might remember that research project I mentioned before that I did a couple of years ago, where I constructed a phylogeny of mosses.

Well, I included genetic data from both Goblin's Gold and M. plumula and our resulting phylogenetic tree indicated they were not closely related. This suggests that their low-light adaptations have evolved twice.

Phylogenetic tree of ~20 mosses from the orders Dicranales and Pottiales.

Bayesian tree obtained from the concatenated rps4, rbcL, and nad5 sequences. Posterior probabilities in bold and parsimony bootstrap support below. Designated as * where clade is not supported in parsimony analyses. Blue shaded branches and family names are currently assigned to Dicranales. Red shaded branches and family names are currently assigned to Pottiales. Family information corresponding to each taxon given on the right side. Outgroup: Sphagnum. Schroers, S. Y., Jeton-Groffman, D., Moodie, I. R., Lagos Oviedo J. J.

I would love to investigate the evolution of luminescence in mosses more comprehensively, perhaps combining more extensive genetic data and morphological information! Maybe one day the opportunity will arise :)

Hope you enjoyed this blog, until next time!