For more than 200 years the Sycamore Gap tree stood along Hadrian’s Wall in Northumberland, England. Its dramatic presence growing out of a dip in the landscape made it one of the most photographed trees in England and a national symbol of resilience. 

The tree is a traditional destination for marriage proposals and it is where couples return for a lifetime of anniversaries. It gained worldwide appeal when it appeared in the film Robin Hood: Prince of Thieves. 

So, when the tree was illegally felled on September 28, 2023, by vandals, the loss made worldwide headlines and devastated a nation of people who felt robbed of an integral part of their history.

“I had a phone call that morning from one of our press teams asking if I’d heard about the Sycamore Gap tree being cut down?” said Chris Trimmer, Plant Conservation Centre Manager who remembers starting work that Thursday morning with the shocking news. 

The removal of the tree at Sycamore Gap, Hadrian's Wall, Oct.12, 2023. (Photo: ©National Trust Images/Rebecca Hughes)

For Trimmer and his team at the Plant Conservation Centre the news was more than just shocking. For them, it also meant that the clock was ticking if there was any chance of salvaging the genetic material for propagation of this famous and historic treasure.

“They collected (plant material) on Thursday and Friday, and it was down with us by nine on Saturday morning and that's when I started propagating,” said Trimmer. “Most of that material wasn't very usable for propagation so I literally had to comb through and select the best material which we could use.”

Seedlings of the 'Sycamore Gap' tree sprouting at The National Trust Plant Conservation Centre. (Photo: ©National Trust Images/James Dobson)

Trimmer was able to splice 20 grafts into existing rootstocks that produced nine plants resulting in a handful with buds and 100 seedlings. By December of 2023, a single seed germinated. 

“Our Head of Gardens said it was the best Christmas present he ever had. I mean, at the end of the day, it's a sycamore tree so they do grow like weeds, but this one, because of its cultural history and the association with people, was really important,” said Trimmer.

Plant triage like this is managed by a tiny team of dedicated horticulturalists at the Plant Conservation Centre behind closed doors in an undisclosed location in the UK. They are the guardians and last line of defense for plants against vandals, mother nature and climate change and they safeguard copies of some species that exist nowhere else in the world.

Astronaut, Tim Peake beside Sir Isaac Newton's apple tree at Woolsthorpe Manor, Lincolnshire. (Photo: ©National Trust Images/Paul Harris)

Protecting Plants of Historical Significance

The Plant Conservation Centre (PCC) is part of the National Trust, a conservation charity that supports 220 gardens at historic homes, castles and parks throughout the UK. The half a million plants in their care are living collections that have historic or botanic significance. 

While the plants under the National Trust do not get the same kind of public attention as other national treasures that it oversees like paintings, archaeology and historic furniture, they do require the most amount of care. The Plant Conservation Centre is the linchpin for this critical responsibility.

“Plants obviously have a habit of dying,” said Alison Crook, National Curator of Living Collections. “If we have such an important historic collection of gardens, certainly the largest in Europe in terms of historic plants, then we have a duty of care to look after them.” 

The centre has been around 40 years serving as both a repository and production site dedicated to the propagation and survival of plants that are under threat. The facility also creates backup copies of plants that are in decline or at risk of extinction. 

Though many people have never heard of the Plant Conservation Centre or know of its work, they are likely familiar with some of its more acclaimed residents. 

Before the Sycamore Gap tree, one of the most famous plants at the centre was Isaac Newton’s Apple Tree. It is the centerpiece of Newton’s theory of gravity that was inspired by an apple falling from the tree. 

“We also have one of its seedlings from that tree taken by Tim Peake, the astronaut, up to the International Space Station and then brought back to Earth and germinated,” said Crook.

The ancient Ankerwycke Yew, Ankerwycke, Surrey. (Photo: ©National Trust Images/John Millar)

Then there’s the Ankerwycke Yew tree. It is a tree of significant size, history and legend bearing witness to some of the most prominent moments in English history. It’s where the Magna Carta was signed and where Henry VIII courted Ann Boleyn, the second of his six wives.

“We like to think, wouldn't it have been nice if that was where he proposed? But it's a massive 1,000-year-old yew tree, quite dramatic sort of plant in the landscape. It would have been huge in that era after Tudor times,” said Crook.

The centre’s mission extends beyond preserving the historic and botanic significance of the plants in its care, but also the legendary stories behind them. 

Seedlings of the 'Sycamore Gap' tree sprouting at The National Trust Plant Conservation Centre. (Photo: ©National Trust Images/James Dobson)

Saving Critical Care Plants

Many of the plants taken in at the Plant Conservation Center are considered in need of end-of-life care requiring extensive efforts to save them from extinction. 

“Some of the plants we have here are the only examples there are anywhere in the world. So, we are custodians of those plants,” said Trimmer.

Examples include some varieties of daffodils in the collection that are too rare and endangered to even disclose which is why secrecy is part of the protocol to protect them. 

The facility will never be open to the public and is housed in an undisclosed location in Southwest England in Devon. This is due to the strict biodiversity protocols in place to protect the collections. 

“What we don't want is lots of people coming through the center and potentially bringing in pests and diseases on clothes and shoes. We know it's been proven that a single speck of dirt has carried Phytophthora, which is one of the main diseases we're looking for all the time,” said Trimmer. 

When it comes to identifying endangered plants, the center relies on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. 

Due to the extensive decades of work at the Plant Conservation Centre some of its cultivated gardens serve as a bank of genetic material for plants that are significantly threatened in the wild. If the original species face extinction there is now a way to replace them in the future.

“The idea of in-situ conservation is where you actually put it back and we have that sort of bank of material available to us,” said Crook. “We're kind of seen as safe sites for some of this material, and some new material that's coming in.”

Some of the centre’s most endangered plants include Fitzroya cupressoides, a conifer from Chile that has been logged out of existence; the Tilia callidonta, which only exists in four places in China; and the Sorbus cheddarensis and Sorbus devoniensis, two of 37 endangered species native to the UK that are at risk of extinction.

The growth of a single root can mean the difference between plant survival and extinction for these rare and endangered species.

The stages of grafting in plant propagation at the PCC. (Photo: ©National Trust Images/James Dobson)

The Art & Science of Propagation

Some of the techniques required to keep plants alive are as rare as the plants themselves making the Plant Conservation Centre an institution for the art and science of propagation. 

“Sometimes you get a storm come through and it'll knock down a tree and then suddenly we get a phone call, and we have to basically propagate it in an emergency, and it’s not always at the right time of year,” said Trimmer.

Propagation starts with grafting which requires taking a small cutting and original genetic material from the original and attaching it to a rootstock.

There are six kinds of grafting used at the centre, each requiring delicate horticultural skills. It can sometimes take decades to propagate a single plant. Many plants are propagated by hand, but others are done in a lab through micro-propagation. This meticulous technique is reserved for only the rarest and most unusual species.

“That the material can be in the lab for up to five years before it comes to us, and then another five years before it goes out to a garden. So, it could be up to 10 years’ worth of investment and time and effort into getting that one plant back out. But for us, it's all about saving those particular plants, those varieties, those unique plants which are linked to our properties. So, it doesn't matter how much time it takes,” said Trimmer.

For the last 20 years the Plant Conservation Centre has worked with Duchy College in Cornwall training up and coming experts in micro-propagation with its rhododendron production. Preserving these highly specialized propagation skills and ensuring a new generation of horticulturalists capable of doing them is an important element for plant survival. 

The walled Rose garden at Mottisfont, Hampshire. (Photo: ©National Trust Images/James Dobson)

The Threats From Climate Change

The work at the Plant Conservation Centre is more important than ever as collections age, and the negative impacts of climate change present even more threats to manage. From changes in common weather patterns and more frequent violent storms to pests, diseases and desiccated soil gardens, plants are more vulnerable than ever, sometimes facing multiple threats in the same year.

“We're having groundwater levels changing. When there's heat, there's also drought. And then at other times of the year, we're having flooding. So, the same garden can experience all of these different things that the plant collections are not used to,” said Crook. 

As temperatures rise in places like Hampshire in the south-east of England, rose collections at Mottisfont Gardens that were planted in the 1970s are struggling. The roses, all named after someone famous, are important to cultural history and showcasing the gardeners who created these unique varieties.

“Think about those amazing men and women who spent hours obsessing over trying to breed these plants together and the stories of the plant hunters that went out and collected this material in the first place,” said Crook. “They opened up a lot of conversations and have left a legacy behind of a lot of botanic gardens in these places that wouldn't be there.”

Woodland Rhododendrons in bloom at Powis Castle and Garden, Powys, Wales. (Photo: ©National Trust Images/Paul Harris)

Increasing heat levels puts plants like rhododendrons at critical risk. They have shallow roots and require partial shade, so it takes a minimal rise in temperature to bake the clay soil. Constant watering is not a sustainable option for the 2,500 different rhododendron classifications existing in the more than 100 gardens. 

Another challenge is the year-round heat causing insect populations to survive even through the winter months.

“We're now getting insects from Europe that are considered pests in our environment and they're not dying over winter anymore because it's not getting cold enough. We've got oak processionary moths, we've got ash dieback, we've got sudden oak death. All our iconic trees in the landscape are under attack from new things,” said Crook.

The centre has responded by adapting its grafting techniques so propagation can take place during times of the year that are not normally suitable.

“We used to be able to graft trees from November through to the end of March. But now we're lucky if we get January to mid-February, because the temperatures are just fluctuating so much day in and day out,” said Trimmer.

One of the adaptations is a method called hot piping that speeds up the grafting process. This solution works for now, but eventually the grafting units may have to move to a cold store facility to ensure a consistent temperature. 

In the vaults at the Millennium Seed Bank at Wakehurst. (Photo: ©RBG Kew)

A Global Effort 

Climate change is not the only threat to plant species globally which is why it is vital that conservation stakeholders work together moving forward. Networks like the Botanic Gardens Conservation International (BGCI) enable data-sharing for plant species through a network of botanic gardens and interested parties like the Plant Conservation Centre.

Other networks, like the Kew Millenium Seed Bank Partnership unites entities globally with collaborations of seed collection, conservation, research and promoting cross-border responsibility for species conservation.

“Kew is primarily a UK-based institute with a global vision and outreach; we can bring about change, but not on our own,” said Timothy Pearce, Conservation Partnership Coordinator for the Millennium Seed Bank. 

As the world’s leading plant science institute, the Millenium Seed Bank operates beneath England’s Kew Gardens in Sussex. Its underground collection houses more than 2.4 billion seeds from around the world in bomb, flood and radiation-proof vaults within sub-zero chambers.  

The MSB’s sole purpose is protecting seeds away from their natural environments and bringing together experts who can safeguard plant species for the future. Partnerships are the cornerstone of its commitment to protect plants and fungi as documented in its Manifesto for Change.

“It takes science to better understand the plants we are dealing with, socio-economics to engage with the custodians of natural areas and habitats, political will to commit to targets, international resourcing to bring all this together,” said Pearce.

Moving plants around the site at the PCC. (Photo: ©National Trust Images/James Dobson)

There is irony in the idea that saving some of the most visually recognizable global treasures like the Sycamore Gap Tree, Isaac Newton’s apple tree and prestigious rose garden collections happen with meticulous work behind closed doors in secret locations. 

With two in five plant species estimated threatened with extinction this work is more important than ever.