Fire and the dragon leaf

Smaug the Magnificent (and excerpt from John Howe).

Dragons.

Huge, fire-breathing, flying reptiles. Sometimes cunning, sometimes chatty, often noble and inscrutable, occasionally savage and despicable. Always covetous of gold and precious items.

Dragons are probably the fantastical creature that has most permeated our modern world. Everyone knows about dragons. Every region has a kind of dragon.

I’ve never been a huge fan of dragons. Shop that sells crystals, incense and fairies, always sell lots of dragons as well. None of those things turn me on. I don’t want a dragon poster, or a statue, a candle, or a chess set.

I’ve played D&D for 40 years now, usually as the DM (running and designing game play). In all that time there have been plenty of dungeons (hundreds) and probably, hmmm, three dragons.

Dragons weren’t a big part of my childhood reading. There were no dragons in The Dark is Rising series, basically none in the Narnia stories (apart from Eustace turning into one, which didn’t count), none in the Alan Garner books, none in the King Arthur series.

Tolkien’s Smaug doodle from the map in The Hobbit.

The one major exception was in Tolkien’s The Hobbit. A major player in the story is Smaug, a giant red dragon. “There he lay, a vast red-golden dragon, fast asleep; a thrumming came from his jaws and nostrils, and wisps of smoke, but his fires were low in slumber.” Smaug ticks all of the boxes as a dragon. He hoards treasure, is extremely intelligent, suave in his conversation and terrible in his temper. However, in the whole of Middle-Earth he is the only dragon left. Smaug comes across as a force of nature.

To me, though, dragons still come across as big, flying lizards, with warm breath, supremely narcissistic and selfish, with compulsive collecting disorders. Like I said, I don’t really see the appeal.

But people seem to love them. They put them on flags, name sports teams and tv shows after them, even have them as one of the 12 Chinese zodiac year symbols (the only mythical species). And so, I find myself working on a plant genus named Dracophyllum, or ‘dragon leaf’.

The pines were roaring on the height, The winds were moaning in the night. The fire was red, it flaming spread; The trees like torches blazed with light. (JRR Tolkien, The Hobbit)

Dragons breathe fire. Smaug made the area around the Lonely Mountain a wasteland by burning the trees down. Presumably dragons are also reasonably fire-resistant. You would not be well-adapted if your own fire burned your own flesh.

New Zealand Aotearoa has become Middle-Earth due to the success of Peter Jackson’s movies and the upcoming Amazon streaming series. So just how flammable are the plants of New Zealand? Would they be susceptible to fiery lizards?

New Zealand is not a very fire-prone part of the world. If we look across the ditch at our colleagues in Australia we see whole ecosystems that are built around frequent fires. Plants have many flammability traits that allow them to survive or at least prosper in a fire ecosystem.

Dracophyllym : I’m sticking with my idea that the leaves look like dragon’s flames. Image by Adrian Paterson.

In Middle-Earth it is different. New Zealand does not have a long history of fires. For the most part we are a damp place with a relatively short history of human occupation (the species responsible for the majority of fires in most parts of the world). It is not a given that plants here would have any sort of flammability traits in New Zealand as they would seldom be very useful. There would be no consistent selection for these traits.

This makes New Zealand an ideal place to test whether plant flammability traits are emergent (arise in response to frequent fires) or incidental (are present in plants for other reasons and just happen to be useful for dealing with occasional fires). That’s where the dragon leaf comes in.

Dracophyllum species are found in Australia and New Caledonia but are most diverse in New Zealand (35 species). I like to think that they are named ‘dragon leaf’ because their leaves and end branches look like dragon flame. However, and a little boringly, they are named this because of a resemblance to a plant group found throughout much of the world, Dracaena, which is Latin for ‘female dragon’ (I’ve never actually seen a female dragon but I am fairly sure that they don’t look like Dracaena!).

Lincoln University PhD student, Xinglei Cui, under the supervision of Tim Curran and Adrian Paterson, set out to look at the variation of traits associated with flammability. He wanted to test a species that was found throughout New Zealand, had high diversity, and was found in many different habitat types.

Dracophyllum ticked those boxes. He collected samples from 21 different species of Dracophyllum. Species range from ground-hugging shrubs to trees of 14m in height.

Xinglei measured habitat aspects at each sample location and then took those sample to be burned in the lab. He measured ignitability (how long it took to catch fire), maximum temperature, sustainability (time spent burning) and consumability (what remained). Xinglei then looked at how evolutionary related the species were.

Dracophyllum on a dry hillside at Porter’s Pass in the Southern Alps. Image by Adrian Paterson.

Species varied wildly. In a paper in New Phytologist, Xinglei reports on his findings. Some species were very flammable and others were not. There was some link to how small the leaves were. There was no real link to habitat – dry areas where fires are more common did not possess species that had more flammable traits.

Overall, Dracophyllum species in Middle-Earth seem to support the idea that flammability traits might be incidental. For example, small leaves are useful for frost protection, water conservation and browsing protection, all problems that New Zealand plant species face. The fact that this also helps with the occasional fire is useful but is not the reason for the traits being present in the plants.

Like their namesake, some Dracophyllum species are more able to resist fire than others. So if Smaug does turn up, then some of our ‘dragon leaves’ might persist in the desolation caused by dragon fire.

Adrian Paterson is an Associate Professor at the Department of Pest-management and Conservation at Lincoln University. His research ranges from biodiversity and biogeography of insects and spiders to behaviour in conservation and wildlife management of mammals and birds.

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