environment

Botanic gardens a barometer for loss

As Botanic Garden Day approaches, Farah Hancock visited Auckland Botanic Garden to learn what role botanic gardens play in modern times.

There’s a tree on the side of the road in Miranda that is slowly dying. The 2018 summer storm which hit the Firth of Thames, sweeping a deluge of sand and sea over land, inundated the tree with salt water.

It’s something that keeps the curator of Auckland Botanic Gardens up at night. Even though it's one tree and not even a rare tree, it’s a big deal.

That one tree, a coprosma propinqua, or mingimingi, is host to a species of mistletoe. For the past 20 years Bec Stanley has been visiting the tree to show the mistletoe - which clings to the tree and taps its water - to conservationists.

Miranda's mingimingi. On the left after the tidal flood January 2018 with leaves already yellowing. On the right in April 2019, dying. Photos: Bec Stanley

“Life’s tough if you are a mistletoe. Your fruit has to be eaten by a bird and then pooped out by that bird onto a plant and not any plant, a host plant of that mistletoe. The chances of that happening these days with fewer birds, fewer plants - the chances are so slim - that’s it’s almost a statistical anomaly.”

Outside of the botanic gardens, Miranda’s roadside tree is one of the few host trees Stanley knows of with the mistletoe growing in it in Auckland.

She thinks Auckland is a bit of a canary in the coal mine for species loss. Fragmented populations are vulnerable one-off events.

“I can’t stop the sea from coming in and inundating that mistletoe, that just happened in a really big storm. Some of our plants are in such small numbers and such precarious places that just one event could wipe them out. I don’t know what that one event will be or when it’s going to happen,” said Stanley.

Auckland Botanic Gardens botanical records and conservation specialist Emma Bodley has been busy playing the role of birds, minus the digestion bit, with the mistletoe’s seeds.

Painstakingly she has removed the seeds from the sticky fruit and spread them in the branches of host trees at the gardens. She estimates she’s placed 100 to 200 seeds in branches and 20 have germinated.

The Ileostylus micranthus mistletoe is a hemiparasite. It takes water from the trees it lives in, but produces its own nutrients through photosynthesis. Pictured is the ball formed where it attached to the host tree, and its seed-containing yellow fruit. Photo: Farah Hancock

Teaching, learning and a back-up

The 20 plants Bodley has grown are now a back-up Auckland population of the mistletoe. This type work being done with the mistletoe seeds represents a big part of the modern role of botanic gardens.

Stanley explains botanic gardens have made reinvention a habit.

Originally botanic gardens were giant medicine chests for monks. Then in the Victoria era they evolved into “gotta catch them all” repositories where plants from around the world were hoarded and cultivated.

“If Queen Victoria said she wanted a mangosteen, everyone went off looking for a mangosteen. Times have changed,” said Stanley.

Now their focus is education, research and conservation,

Auckland Botanic Garden does a bit of all three. Around 120 school students visit the gardens each weekday, and the gardens has research partnerships with universities.

Its threatened species garden will be an area Stanley will show off to visitors on Sunday during the Botanic Gardens Day tours. The garden conserves plants and raises public awareness.

It tries to recreate some of the different environments the species might be easily found, if they weren’t so threatened. There’s coastal, salt marsh, open spaces and even island habitats.

By some people’s standards it’s not a particularly attractive garden, and volunteers working in the area are watched closely. There’s a very real chance a good-meaning volunteer could unwittingly wipe out a threatened plant.

Signs throughout the garden yell “Not a weed!”.

A puha, strangely enough, is in the garden. It’s the original native puha, with chewier-looking leaves than what’s eaten now. The current puha is an exotic doppelganger that has slowly edged out the original, taking its place and name.

Stanley said although the native version flourishes in the threatened species garden, she’s never seen it in the wild. She’s been unable to find out how the original, with its tougher leaves, was prepared.

“A loss of plants means a loss of culture. As this plant got lost and became uncommon, the cultural stories to it have been lost as well. I’m hoping there are people out there who still remember.”

Another native plant is so small, just a few microscopic leaves peek out of dirt and it’s hard not to wonder if you’re being pranked by the staff. The parahebe jovellanoides was once nicknamed “bamboozle” because no one was sure what it was. Only three plants have been found in the wild. When in flower, it's covered with small white and purple blooms.

The Kunzea sinclairii is a kānuka which instead of growing upright uses boulders as a chaise longue. Photo: Farah Hancock

Other plants in the threatened species garden look less like weeds, and more like mutated versions of commonly seen plants.

There’s a kānuka, which instead of standing upright to attention as it does on the banks of motorways, reclines languidly over boulders. It’s found in rocky outcrops of Aotea Great Barrier Island and its conservation status is listed at nationally critical. Bodley has been working with the United Kingdom’s Millennium Seed Bank funding and the Department of Conservation to collect seeds.

Clianthus puniceas, commonly known as the kakabeak, is currently in flower at the Auckland Botanic Gardens. Photo: Farah Hancock

The show pony of New Zealand threatened plants is here too. Clocking in as the most conventionally attractive plant in the garden is the clianthus puniceas, commonly known as the kakabeak for its beak-shaped bunches of red flowers. Only one plant exists in the wild and Bodley is busy squirrelling seeds away.

As well as being beautiful, the plant is tasty - particularly to rabbits. Even in the confines of the botanic gardens it needs its own rabbit-proof fence.

“If one rabbit comes, they find this plant,” said Stanley.

Unruly tourists and empty vaults

There’s a multitude of reasons why plants are threatened. Invaders like hungry rabbits, deer and possums play a part. Even exotic garden snails can be a problem. As Stanley points out, it can be feasible to wipe out rats on offshore, predator-free islands but getting rid of garden snails can be almost impossible.

Other species of plants become unruly tourists, which have defied deportation orders and taken over spaces native species once thrived in.

Climate change will also play an increasing role. Storms like the one killing the lone tree at Miranda will likely wreak havoc on precarious plant populations, and rising temperatures could change ecosystems.

Stanley said Australian botanic gardens focus a lot on climate change-related plant issues and it’s something she thinks will become a bigger issue for New Zealand. She sees value in creating a network of botanic gardens which could work together to conserve species.

One thing she and Bodley worry about is a lack of resources. New Zealand does not have a seed bank for native plants.

What it has is one shelf in an agricultural seed bank. A non-government organisation raised $60,000 to secure the shelf in the Margot Forde Forage Germ Plasm Centre in 2012. Stanley and Bodley worry these funds might soon be exhausted.

“There’s a really, really clear need for a national seed bank.”

Bodley, who recently visited a seed bank in Australia described it as “lightyears” ahead of New Zealand and like visiting Disney Land.

Until a New Zealand seed bank exists, Stanley, Bodley and the team are busy doing what they can to preserve Auckland’s threatened species. The gardens are happy to help home gardeners interested in incorporating some of the species threatened in the wild into suburban backyards.

Stanley is hosting a free tour of the threatened species garden on Botanic Garden Day this Sunday.

Newsroom is powered by the generosity of readers like you, who support our mission to produce fearless, independent and provocative journalism.

Become a Supporter

Comments

Newsroom does not allow comments directly on this website. We invite all readers who wish to discuss a story or leave a comment to visit us on Twitter or Facebook. We also welcome your news tips and feedback via email: contact@newsroom.co.nz. Thank you.

PARTNERS