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The number of plants that have disappeared from the wild is more than twice the number of extinct birds, mammals and amphibians combined. The new figure is also four times the number of extinct plants recorded in the International Union for Conservation of Nature’s red list.

It takes many years to be sure a plant has been wiped out, meaning there are many species awaiting formal confirmation. “How are you going to check the entirety of the Amazon for your lost plant?” Vorontsova said. And some plant species may have gone extinct before ever being discovered. Botanists find about 2,000 new species a year.

The plant analysis found Hawaii had the most recorded extinctions (79), followed by the Cape provinces of South Africa (37), with Australia, Brazil, India and Madagascar also among the top regions. However, there may well have been as many extinctions in places that have been less well studied.

The main cause of the extinctions is the destruction of natural habitats by human activities, such as cutting down forests and converting land into fields for farming. Vorontsova saw this firsthand in Madagascar when searching for an unusual-looking grass, Sartidia perrieri, that was collected just once, in 1914.

“We scoured the hills and mountains … but it was not there,” she said. “In the places where it would be growing, there are cattle grazing, regular fires and people growing rice.” Vorontsova’s search for spiny wild aubergines in Tanzania and Kenya ended the same way. “We found a coastal forest completely destroyed. I was shocked.”

The database of plant extinctions is the result of years of scouring scientific journals and fieldwork reports. The scientists expect it will help conservation in the future by highlighting what types of plants are particularly vulnerable to extinction. For example, location is a more important factor than type of plant: those on small islands or in areas with a Mediterranean climate are more at risk, whether they are roses, orchids or palms.

“Millions of other species depend on plants for their survival, humans included, so knowing which plants we are losing and from where will feed back into conservation programmes,” said Nic Lughadha.

Alan Gray, of the UK’s Centre for Ecology and Hydrology, said: “Scientists have not studied the vast majority of the world’s plants in any detail, so the authors are right to think the numbers they have produced are large underestimates. To address this extinction crisis, humanity will need to devise solutions that target funding towards conservation research and action. It’s time to ask not what biodiversity can do for us but what we can do for biodiversity.”