A sweeping new analysis in the journal Science has delivered the first comprehensive assessment of extinction risk across all 335,497 known species of flowering plants, finding that more than one-fifth of the evolutionary history carried by Earth’s angiosperms faces potential extinction — a crisis that has remained largely invisible to conservation science for decades.
A Conservation Blind Spot Finally Addressed
For nearly 20 years, a metric called EDGE — Evolutionarily Distinct and Globally Endangered — has helped conservationists identify animals in urgent need of protection. Developed by the Zoological Society of London in 2007, the tool combines a species’ extinction risk with how genetically unique it is within the broader tree of life. It spotlighted overlooked creatures such as the aye-aye, pangolin and axolotl — animals that represent irreplaceable evolutionary branches but rarely appear on conservation magazine covers.
Plants were left out. Completely.
Rikki Gumbs of the Zoological Society of London, who co-led the new analysis, said the imbalance stemmed from a data problem, not a lack of importance. For nearly two decades, plants were dismissed as mere backdrop for photographs of bees and tigers, he noted, while conservationists lacked the scale of information needed to assess the botanical world.
Building the Largest Species-Prioritization Database Ever
The project, 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, constructed a tree of life and generated extinction-risk estimates for every known flowering plant species on the planet. Researchers assigned EDGE scores to all 335,497 angiosperm species using molecular data cross-referenced against the IUCN Red List of Threatened Species.
Forest described the undertaking as unprecedented. Angiosperms outnumber the largest previously EDGE-assessed animal group — ray-finned fish — by more than tenfold. The scores now provide what he called vital information needed to spotlight irreplaceable, threatened species that conservation efforts have often overlooked, in service of benefits that all life on Earth depends on.
The Stark Number: 21.2% at Risk
The headline figure is sobering. The team estimates that 21.2% of angiosperm evolutionary history is at risk of extinction, and has identified 9,945 priority species that disproportionately account for that threatened diversity.
To put that in perspective: the risk is nearly double the equivalent figure for jawed vertebrates — a group encompassing everything from sharks to elephants — where the rate sits at about 13%.
The 9,945 species carrying that risk represent roughly 3% of all known flowering plants. But their evolutionary weight is disproportionate to their numbers. Losing them would mean removing branches of the plant tree of life that took tens of millions of years to grow — branches that cannot be recovered once gone.
Sven Buerki, a botanist at Boise State University and a contributor, 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. By contrast, more than 80% of vertebrate groups have been assessed. Plants, he said, have been dying in the dark.
Familiar Names, Ancient Lineages
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 them for urgent attention. So do relatives of the corpse flower, whose rare, cavernous blooms draw crowds to botanical gardens.
Perhaps stranger is 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. Today, fewer than 100 mature jellyfish trees survive in the wild, confined to four small populations. With no close living relatives, its loss 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 Tool for Triage, Not Just a Eulogy
Despite the grim arithmetic, the study’s authors frame their findings as a roadmap rather than an obituary. The researchers calculate that protecting just 5.9% of species, selected by EDGE ranking, would safeguard half of all threatened angiosperm evolutionary history. Protecting the full EDGE list would preserve 16.6% of it.
With finite conservation budgets and infinite need, EDGE scores offer a way to triage 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.
Broader Implications for Biodiversity Policy
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 world sustaining them. Gumbs captured 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.