How teabags of fungi are saving native orchids from extinction

Unlike their flashy tropical cousins, Aotearoa’s native orchids are tiny and ‘not very showy’. This apparent lack of charisma hasn't stopped scientists from Te Papa and Ōtari-Wilton’s Bush saying they’re an important part of our natural heritage and worth saving.

If Wellingtonians spot teabags stapled to trees in the bush around the city they should not be tempted to brew a cuppa – they’re part of a native orchid conservation project and the culmination of several years’ scientific research.

Karin Van Der Walt, Ōtari-Wilton’s Bush conservation and science adviser, says New Zealand doesn’t do enough for plant conservation compared to the efforts to save our threatened animals.

“Kiwis are really cute, they’re cuddly and people like doing conservation for them. But I think there are about 70,000 of them. Some of these orchids may be down to less than 20 individuals.”

“It’s just a tiny plant, but it’s our tiny plant. And if New Zealand doesn’t look after it, they’re gone,” Van Der Walt told 1News.

In an attempt to avoid this fate for some of our most threatened orchid species, Ōtari-Wilton’s Bush, in collaboration with Te Papa, are developing techniques to restore the populations of these orchids for the first time in New Zealand, with teabags an important part of the mix.

Botanists have been interested in New Zealand’s orchids for a long time – Joseph Banks and Daniel Solander collected several of our orchid species during Captain Cook’s first expedition to Aotearoa.

The carefully pressed specimens travelled to London on the Endeavour, narrowly escaping being thrown overboard when the ship came into difficulty on the Great Barrier Reef and Cook ordered his men to lighten the load. The canons went over, but remarkably the botanical collections were spared.

Now, more than 250 years later, the orchids are back in New Zealand where they form part of Te Papa’s herbarium, under the close watch of botany curator Carlos Lehnebach.

Lehnebach is originally from Chile, where orchids have large brightly coloured flowers and grow 1 metre high, but his fascination with Aotearoa’s diminutive orchids drew him down under.

“When I came across my first book of New Zealand orchids I saw these tiny little wee things, they were green and black, no colours, weird shapes and sizes and habitats. I just went completely crazy about them,” he said.

There are 110 known species of native orchids, seven of which Lehnebach has described and identified.

They’re found from mountaintops to wetlands, and the more ‘weedy’ species even pop up in our backyards. Some are the size of a fingernail when fully grown.

Whilst some of our orchids are abundant, 35% are a conservation concern, with a number of species classified as nationally critical, some with very small populations of plants only found in a single spot in the country, leaving them particularly vulnerable to being wiped out by events such as fires or slips.

Lehnebach says the main threats to our orchids are human-induced, such as habitat destruction through the draining of wetlands and deforestation, and the illegal collection of orchids from the wild. Animal damage from wild pigs is also an issue, and the potential impacts of climate change are yet to be clearly known.

One of the orchids collected so long ago by Banks and Solander – the perching orchid – is now part of the Lottery-funded conservation project that’s developing techniques to restore the populations of the five most threatened orchid species in the Wellington region.

The rarest is the potato orchid, found in one spot in the Wairarapa and in a handful of places in the South Island.

Van Der Walt says when they checked in on the Wairarapa orchids there were only ten plants, and they have concerns about the future stability of the site.

“They’re growing on a steep bank, and part of the bank has already eroded with all rain that we’ve had.”

Only a few potato orchids were found in the South Island this year, although Van Der Walt notes they are very hard to spot even when you know where they are.

“It literally looks like a stick that’s producing little white flowers. It’s very complicated to work with these plants. It’s very easy to drop over the edge so that it’s in a decline that you can’t halt,” Van Der Walt said.

She, Lehnebach and the team are also working with five more common ‘surrogates’, orchid species closely related to the rare ones, that they can use to refine their techniques without risk to the threatened populations.

Although orchid conservation is a well-established field internationally, the project is a first for Aotearoa. Van Der Walt suggests the complexity of orchids is the reason we’ve lagged behind.

“What’s really difficult about orchids is their seeds are very, very small - minute. And they’ve got this really complex relationship with fungi, so they need a fungal partner to be able to germinate the seed.

“So you’re effectively not only working with the orchid, you’re working with the fungi as well.”

This requires a lab, and some high-end skills and knowledge in orchid taxonomy, seed and fungi biology and DNA extraction that up until this project had never been brought together in New Zealand for this purpose.

Orchids seeds have evolved to become small and light so they can be easily carried by the wind. They’ve done this by jettisoning the food source found in other seeds, and stripping things back to the bare basics of just a plant embryo with a tiny cover.

This is where the fungal partners come in.

“The fungus, it’s like an umbilical cord. [It ]helps to bring the nutrients and the food into the seed, so the embryo can start developing and growing,” Lehnebach said.

So, whereas for other plants it can be possible to restore threatened populations with seeds alone, to conserve orchids the fungal partner is also needed.

To identify the right fungus for each species, the project team take a small piece of root from adult plants in the wild.

Back at the Lions Ōtari Plant Conservation Laboratory the root goes under the microscope, and the various fungi growing within the root are teased out and put onto petri dishes to grow. For some of the orchid species they’ve found fungi from up to eight different families in the root.

The fungal samples are DNA sequenced and are then put together with the seeds into an incubator to see if the magic relationship blossoms between fungus and seed.

It can be a long wait to see if the matchmaking has been successful and germination has occurred - up to five months.

“It teaches us patience,” says Van Der Walt, who is delighted with the results they’ve achieved. They’ve identified the fungal partners for four-out-of-five of the threatened orchids so far, and for all of the surrogate species.

The lab is now home to more than 200 orchid seedlings, at various stages of being hardened off to get them prepared for life outside the cosy and comfortable laboratory.

“There’s a lot steps involved. What we’re trying to do is understand is what works and doesn’t work at each step.” says Van Der Walt.

Once they’ve identified the fungal partner, Van Der Walt and research technician Jennifer Alderton-Moss add the seeds and the fungus to Ōtari's cryopreserved seed bank, creating a ‘backup’ that could potentially last thousands of years.

The samples are frozen in liquid nitrogen at -196C, where they’re kept for posterity in case they’re needed in the future for conservation purposes.

“It’s a great solution… in a couple of years if one of the populations is wiped out, we will have this backup [of] seeds and fungi that will allow us to reintroduce this species into the wild. It’s a game changer,” says Lehnebach.

For the perching orchid, they’ve reached an exciting stage – taking seeds and their fungal partners back to a site in the bushy hills above Wellington, to see if they’ll grow.

High-tech scientific equipment is no longer involved, just humble teabags, a stapler, and some cut-up pantyhose - Van Der Walt jokes that she got some funny looks on the bus carrying ten packets of tights.

The teabags contain the orchid seeds and their fungal partners and the hope is they’ll germinate, attach to the tree and grow.

It’s a huge milestone for the team, and if it’s successful will mark the beginning of the restoration of the population in the wild.

“There’s actually so much work that’s happened before, and so much time and effort that we try to understand stuff,” says Van Der Walt.

“So it’s really rewarding to know this is the final stage of taking all that complicated information and have it in a teabag, basically, and put it on a tree.”

Van Der Walt expects to follow a similar method with the other species, but as they’re orchids that grow in soil rather than in a tree like the perching orchids, they’ll bury the teabags instead.

Her hope is that eventually the techniques they’re developing will be accessible for native nurseries and community groups interested in orchid conservation.

Lenhebach, who’s dedicated a significant amount of his career to studying orchids, is also delighted to reach this point.

“It’s brilliant. It’s basically taken over 20 years to achieve this dream that I had, to be able to actually save our orchids from extinction.”