When Gold Coast botanist Lui Weber went to visit his physiotherapist in 2017 for a sore back, he probably didn’t expect to be inducted into the annals of botanical history – but that’s exactly what happened. As reported by the ABC, Weber, while in his physio’s backyard, noticed an unusual tree that he didn’t recognise, with rough corky bark and slender waxy leaves.
It took four more years of sleuthing, hunting for the flowers and fruits of the tree to play a game of morphological spot-the-difference, before the tree was definitively recognised as a new, undescribed species – Endiandra wongawallanensis.
Endiandra is a genus of about 126 plant species of the laurel family, found across South-East Asia, Australia and the Pacific Islands, with 39 species in Australia. Last December, the Queensland Herbarium published a paper describing this new species of Endiandra tree, co-authored by Weber, and thus crystallised it in the botanical zeitgeist as a distinct species.
At a time when millions of species seem to be disappearing by the day, it’s encouraging that “new” organisms are just around the corner or behind the backyard fence, quietly waiting to be discovered. In fact, it’s not actually that uncommon: the Queensland Government says it discovers on average 50 new species of plants, lichens, algae and fungi in the state each year, and scientists reckon there might be 500,000 undiscovered species of plants and animals waiting to be identified across Australia.
All this raises some interesting questions. How can new species of plants still be hiding in plain sight? How do we decide what actually is a new species? And what is the conservation value of doing so?
Hiding in plain sight: Australia’s biodiversity
“Australia is one of the mega-biodiverse countries of the world,” says Michelle Waycott, chief botanist at the State Herbarium of South Australia and professor in the School of Biological Sciences at the University of Adelaide.
“There’s a lot of reasons for that – our long evolutionary history, our isolation from other parts of the world, and also the amazing range of environments that occur across the landscape.”
This extraordinary biodiversity – and the diversity of our landscapes – equates to a species richness that goes some way to explaining why new organisms seem to appear right in front of our eyes, year on year.
Added to that, Australia’s weather patterns can vary wildly thanks to phenomena like La Niña, which can draw out usually dormant organisms.
“At the moment, the Nullarbor is blooming with flowers because we’ve had two La Niña years,” says Waycott. “So, we’re starting to see lots of things flowering that you might only ever see if you’re able to be there within a month of the rain.”
But Waycott says there’s also less interest in taxonomy from broad swathes of the scientific community today than in the past, so fewer people are setting out to discover new species in the first place.
“Taxonomy has become a less popular activity in the sciences over the last 20 years,” Waycott says. “It’s assumed that we know more about our biodiversity than we do, and so fewer people are looking at the collections that have been made.”
Nonetheless, a resurgence of citizen science and public interest in taxonomy is helping draw new species out of the woodwork.
“There’s been a resurgence of what I would call community-based taxonomy, where people are looking in their backyard and saying ‘oh wow, this looks really different’.”
How do you actually get a new species recognised?
Let’s say you’ve identified a new species of plant in the forest behind your house. How do you actually go about establishing that new species and, critically, how do you get the scientific community to recognise it? According to taxonomists, it’s a convoluted, step-wise process.
First you have to describe the type specimen.
“The type specimen is the reference piece of plant material, and that material is defined as representative of that species,” says Waycott. “Then you package that up and share it with the public by being published in a journal, and when that’s published that entity has some validity.”
In Australia, the plant must be described and published in the journal of the herbarium of the state it’s found in. But to get that far, you have to find the right plant matter – which means you need the fruits and flowers.
“That’s why it’s taken Lui four years, because he was waiting to find the flowers and the fruit [of Endiandra wangawallanensis],” says Andrew Thornhill, a research associate at the University of Adelaide and the State Herbarium of South Australia, who works on molecular phylogenetic analyses of plants.
“They’re the key features to help you identify the different species.”
But even then, it’s not so simple – because the scientific community can scarcely reach a consensus on what actually constitutes a species, let alone agree on each individual new plant.
What actually is a new species?
“Every species is pretty much just someone’s opinion,” says Thornhill. “They have to describe that in a paper, then two or three people have to read that paper and agree with it so it gets published, but then it has to be accepted by the whole community as well. Just because you publish your name doesn’t mean it gets accepted by everyone.”
According to Waycott, there are all sorts of competing ideas about what constitutes a species.
“Within the taxonomic community there are a range of views on this, and it’s led to different word paradigms,” she says.
“There are many people who would say that the best species concept is what we call the biological species concept,” Waycott says. The biological species concept dictates that if two creatures or organisms can interbreed then they must belong to the same species, because they’re not genetically isolated enough.
“That’s a very good basic concept to follow if you’re a mammal, but unfortunately plants don’t behave quite so clearly,” she says. “They have a whole range of ways of breeding that means that you could integrate, even though you’re completely unrelated.”
Waycott says eucalypts are a prime example of this: recent research suggests that eucalypts that are evolutionarily isolated for millions of years can still interbreed, because the barriers to the exchange of pollen and egg are low in the Myrtaceae family to which eucalypts belong.
“That’s why we have so many hybrids popping up.”
In fact, this hybridisation process has been known to befuddle taxonomists. Eucalyptus paludicola is a tree found on the Fleurieu Peninsula and Kangaroo Island in South Australia. First described in 1995, it was classified as endangered and so benefited from all the federal protections that classification afforded.
But in 2020, a study published in the journal Diversity revealed that genomic screening had outed E. paludicola as a fraud; it was not, in fact, an isolated species, but a “transient hybrid entity”– that is, a hybrid between two relatively common eucalypts, E. ovata and E. cosmophylla.
What’s more, this hybrid was a phylogenetic cul-de-sac: “It wasn’t actually making any fertile seeds,” says Thornhill. “Some hybrids might, but this one wasn’t, so every time a hybrid appeared it would grow, live and die. It’s a dead end.”
That’s where DNA comes in. Genetic analysis was what revealed E. paludicola as a hybrid, and it’s this kind of analysis that some researchers say should be used to define a species concept.
“There’s instances where species have been defined purely on the basis that they have a distinctive DNA profile,” says Waycott. But, in some cases, those species are very difficult to distinguish morphologically.
“This is where that controversy comes,” Waycott says. “If you can’t observe the differences, how can you tell what you’re looking at – we’re not going to run around with the DNA barcodes and poke them at every plant or animal to try to work out what they are.”
And that’s important, because the crux of the whole issue of defining a species is that it can help you to understand what’s rare and what’s common – and therefore, what might need conservation help.
“There needs to be a compromise,” Waycott says, between phylogenetics and more traditional approaches.
“Phylogenetics is where you can use the relationships based on DNA sequences to get an insight into the evolutionary history of a group of organisms, independent of where it grows,” she says.
But traditional taxonomy was always based on morphology or geography – how it looks, or where it grows.
“What some people do, and this is often the prevailing method these days, is you look at those phylogenetic clusters, and then try to untangle within those classes how many species you’ve got by applying these morphological characteristics to define them.”
What’s in a name? A whole heap of conservation value, potentially
Refining this process matters, because we need to standardise these species definitions across the country if we hope to conserve them properly.
“In the past, some states would call one plant something, and the other state would call it something else,” says Thornhill. “And that gets confusing, especially when names are applied to conservation, because you might be saying something’s really rare, but actually it’s existing with a different name all over Australia, and you start wasting money on trying to save something that isn’t rare.”
That’s why we now have the Australian Plant Census, to unify these taxonomic units – these species – under agreed national names.
So, while species names may seem like a matter of semantics, they actually matter. In fact, without a name, a species can’t hope to have meaningful protection under federal legislation.
“If you can be defined as a species, you have a greater likelihood of having action being able to be taken,” Waycott says.
But there’s pitfalls here, too: what happens if a species loses its name? That’s a conundrum Waycott is familiar with, and one that vexes the scientific community.
Waycott has recently published a paper explaining that an endangered seagrass species in Florida, US, known as Halophila johnsonii is actually Halophila ovalis, a seagrass native to the Indo-Pacific.
“It’s actually not a species, it’s a relocation of material from the Pacific into the Atlantic,” Waycott explains. “So that species, which has been under conservation protection for many years, they’re in the process of having to de-list.”
Thus, this kind of science comes with acute responsibility.
“We’ve been extremely careful with that research, because we know that by publishing this work we’re going to lead to the reduction of protections of that species, which leads to the reduction of protection of the environment it’s growing in.”
Therein lies a confounding conservation question. Because Halophila ovalis is classified as of least concern globally, it’s not rare and doesn’t need protecting. But the Florida seagrass which has now turned out to be H. ovalis is clearly rare in its context, and forms an integral part of a complex ecosystem. Its disappearance, while not globally destructive to the species, could have serious local implications.
In that light, is a species-based approach always the best way to go?
“Instead of throwing money at one rare thing, maybe we should be throwing money at rare environments,” says Thornhill. “A lot of money is thrown at cute, fluffy things, so if you came up with three new species of koala I bet money would be thrown at every one of them in half a second. Charismatic species get attention.
“But then there’s the whole-environment approach. So if instead of saying ‘save the koala’ we say, ‘save those subtropical forests’, then we would save all the trees there too. And that’s what we’re trying to do.”
Waycott agrees. “We need to think about the future, about how we can use taxonomy as a tool because it’s fundamental. But we should also be thinking more broadly about protecting biodiversity on a larger scale.”