New global assessment of 335,000 species reveals botanical world’s hidden crisis, with vanilla orchids and jellyfish trees among those at greatest risk.
For nearly two decades, conservation science developed sophisticated tools to measure what the world stands to lose when an animal species disappears. Tigers, pangolins, and axolotls received priority scores. Flowers and trees, by contrast, remained largely invisible.
That imbalance ended this spring. A landmark study published in the journal Science has delivered the most comprehensive diagnosis ever conducted of the botanical world’s fragility: more than one-fifth of the evolutionary history carried by Earth’s flowering plants now faces extinction.
A Metric Built for Animals, Applied to Plants
The tool behind the finding is EDGE — Evolutionarily Distinct and Globally Endangered — a metric introduced by the Zoological Society of London in 2007. The method combines a species’ extinction risk with how genetically unique it is within the broader tree of life.
For nearly 20 years, EDGE scores illuminated the plight of unheralded animals that might not headline a nature documentary but represent entire, irreplaceable branches of evolution. Plants, however, remained what Rikki Gumbs of the Zoological Society of London described as mere backdrop for photographs of bees and tigers.
“Flowers and forests were never simply scenery,” Gumbs said.
The imbalance was never a matter of stakes. It was a data problem. Assessing extinction risk for an animal is one thing; assessing it for roughly 335,000 species of flowering plants — angiosperms — is another matter entirely.
Building a Family Tree for a Third of a Million Species
Led by Félix Forest, a plant evolutionary biologist at the Royal Botanic Gardens, Kew, alongside teams from the Zoological Society of London, Boise State University, and international collaborators, the project constructed a tree of life and generated extinction-risk estimates for every known flowering plant species on Earth.
Researchers assigned EDGE scores to all 335,497 species using molecular data cross-referenced against the IUCN Red List of Threatened Species. It stands as the largest species-prioritization assessment ever undertaken in conservation science.
Forest noted that angiosperms outnumber the largest previously EDGE-assessed animal group — ray-finned fish — by more than tenfold. Compiling comparable data, he said, was no small task.
“The scores now provide the vital information needed to spotlight irreplaceable, threatened species that conservation efforts have often overlooked,” Forest said.
The Number That Should Worry Us: 21.2 Percent
The headline figure is stark. The team estimates that 21.2 percent of angiosperm evolutionary history is at risk of extinction. They identified 9,945 priority species that disproportionately account for that threatened diversity.
To put that loss in perspective: the figure is nearly double the equivalent risk measured across jawed vertebrates, a group encompassing everything from sharks to elephants, where the comparable rate sits at around 13 percent.
The 9,945 EDGE species represent roughly 3 percent of all known flowering plants, but their evolutionary weight is disproportionate to their numbers. Losing them would erase branches of the plant tree of life that took tens of millions of years to grow.
Perhaps the most sobering context comes from how little formal attention these species have received. Sven Buerki, a botanist at Boise State University and a contributor to the study, framed the disparity bluntly: more than two in five plant species are estimated to be threatened with extinction, yet fewer than one in five has ever received a formal threat assessment — compared with over 80 percent of vertebrate groups. Plants, he said, have been dying in the dark.
Faces of the Crisis
Among the newly flagged priority species are some remarkably familiar names. The vanilla orchid — source of the world’s most popular dessert flavoring — now sits among plants whose evolutionary uniqueness and endangerment mark it for urgent attention. It shares that status with the corpse flower’s malodorous relatives, whose rare blooms draw crowds to botanical gardens whenever they open.
Then there is a stranger case: the jellyfish tree, or Medusagyne oppositifolia, found nowhere on Earth except a handful of rocky outcrops on the island of Mahé in the Seychelles. Believed extinct until a few surviving individuals were rediscovered in the 1970s, it is the sole member of its genus, its jellyfish-shaped seed pods giving the species its common name. Today, fewer than 100 mature jellyfish trees are thought to survive in the wild, confined to four small populations near Seychelles’ coast. With no close living relatives, its loss would not just erase a species — it would prune an entire limb from the angiosperm family tree.
Other headline cases include ancient, solitary lineages such as Amborella trichopoda, a modest New Caledonian shrub whose evolutionary lineage split from all other flowering plants some 130 million years ago — making it, by the study’s measure, the single most evolutionarily distinct angiosperm alive today.
A Roadmap, Not Just an Obituary
For all its grim arithmetic, the study’s authors frame it as a tool for triage rather than a eulogy. The researchers calculate that protecting just 5.9 percent of species, selected by EDGE ranking, would safeguard half of all threatened angiosperm evolutionary history. Protecting the full EDGE list would preserve 16.6 percent of it.
That promise is embedded in the metric: with finite conservation budgets and infinite need, EDGE scores offer a way to direct resources toward species whose loss would cost evolutionary history the most.
Some translation from data to action is already underway. Buerki said his team’s goal is to fold the results directly into Flora of the World, an online platform, so that anyone searching for a species can see not just where it grows, but how evolutionarily irreplaceable — and how endangered — it is. At Kew itself, the EDGE metric has already begun shaping decisions inside the institution’s Living Collections, guiding which specimens horticulturists prioritize for cultivation and seed-banking.
Why It Matters Beyond the Greenhouse
The paper’s authors situate their findings within a broader argument that has circulated in conservation biology for years but rarely with plants at its center: global biodiversity policy has consistently treated evolutionary diversity as something worth protecting, yet plants were left out of the assessments meant to operationalize that principle.
That taxonomic imbalance, the authors argue, has undermined plant conservation for decades, even though the preservation of evolutionary lineages underpins both the immediate benefits people draw from ecosystems and the future of life on Earth more broadly.
It is a reminder that the animals typically pictured on the covers of conservation reports — pandas, polar bears, tigers — depend ultimately on the quieter, rootier world sustaining them. Gumbs’s framing captures the stakes succinctly: flowers and forests were never simply scenery. They are, this study suggests, running out of time on their own terms — and now, for the first time, science has the numbers to prove it.