For decades, conservation science has quantified the looming loss of tigers, coral reefs, and charismatic megafauna while largely ignoring the botanical world that underpins all terrestrial life. That imbalance ended this spring when a groundbreaking study published in the journal Science delivered the most comprehensive assessment ever conducted of flowering plants’ evolutionary vulnerability: more than one-fifth of the evolutionary heritage carried by Earth’s 335,000 angiosperm species now faces extinction.
From Animal Conservation to Botanical Triage
The analytical engine behind the findings is EDGE — short for Evolutionarily Distinct and Globally Endangered — a metric developed by the Zoological Society of London in 2007 that marries a species’ extinction risk with its genetic uniqueness on the tree of life. For nearly two decades, EDGE scores have spotlighted overlooked animals such as the aye-aye, pangolin, and axolotl — species that, while not documentary stars, represent irreplaceable evolutionary branches.
Rikki Gumbs, a conservation scientist at the Zoological Society of London and co-lead author of the new analysis, highlighted the persistent blind spot. For almost 20 years, he noted, this approach has allowed conservationists to identify neglected animals urgently needing protection, while plants remained essentially invisible — dismissed, in his words, as mere backdrop for photographs of bees and tigers.
That neglect was never about stakes. It was a data problem. Assessing extinction risk for an animal is one task; assessing it for approximately 335,000 flowering plant species across every global ecosystem is a challenge of vastly different magnitude.
Constructing an Encyclopedia of Botanical Life
Led by Félix Forest, a plant evolutionary biologist at the Royal Botanic Gardens, Kew, alongside researchers from the Zoological Society of London, Boise State University, and international partners, the project undertook an unprecedented mission: build a comprehensive tree of life and generate extinction-risk estimates for every known flowering plant species on Earth.
The team assigned EDGE scores to all 335,497 angiosperm species using molecular data cross-referenced against the IUCN Red List of Threatened Species. This represents the single largest species-prioritization assessment ever undertaken in conservation science.
Forest contextualized the undertaking’s scale. Given that angiosperms outnumber the largest previously EDGE-assessed animal group — ray-finned fish — by more than tenfold, compiling comparable data for flowering plants was, in his description, no small task. The scores now provide vital information needed to spotlight irreplaceable, threatened species that conservation efforts have often overlooked, serving the benefits — current and future — that all life on Earth depends upon.
The Stark Arithmetic: 21.2 Percent at Risk
The headline figure commands attention. 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. For perspective, that figure is nearly double the equivalent risk measured across jawed vertebrates — a group encompassing everything from sharks to elephants — where the comparable rate hovers around 13%.
These 9,945 so-called EDGE species represent roughly 3% of all known flowering plants, but their evolutionary weight far exceeds their numbers. Losing them would mean severing branches of the plant tree of life that required tens of millions of years to grow and cannot be recovered once gone.
Sven Buerki, a botanist at Boise State University and study 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 — compared with over 80% of vertebrate groups. Plants, in other words, have been dying in the dark.
Familiar Names, Extraordinary Risks
Among the newly flagged priority species are remarkably recognizable names. The vanilla orchid — source of the world’s most popular dessert flavoring — now ranks among plants whose evolutionary uniqueness and endangerment demand urgent attention, alongside relatives of the corpse flower, whose rare, cavernous blooms draw crowds to botanical gardens whenever they appear.
Then there is a stranger case: the jellyfish tree (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 the Seychelles coast. With no close living relatives, its loss would not merely 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 an Obituary
For all its grim arithmetic, the study’s authors frame their work as a tool for triage rather than a eulogy. The researchers calculate that protecting just 5.9% of species, selected by EDGE ranking, would safeguard half of all threatened angiosperm evolutionary history — and that protecting the full EDGE list would preserve 16.6% of it. With finite conservation budgets and infinite need, EDGE scores offer a strategy 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 aims 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.
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 — for decades — were excluded from 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 conservation report covers — pandas, polar bears, tigers — depend, ultimately, on the quieter, rootier world sustaining them. Gumbs’ 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.