Humanity is "staring down the barrel" of potentially losing up to half of its future medicines because so many plant species are facing extinction, scientists have warned.

Nearly half of all those that flower are threatened, amounting to over 100,000, while it is believed that around 77% of all those as yet undescribed by science are at risk.

In some cases they are going extinct between the time of first discovery and when they are cataloged, which takes around 16 years on average.

The main cause of these extinctions is , such as deforestation or the construction of dams which flood river areas further upstream.

Climate change is "certainly on the horizon," said conservation analyst Matilda Brown, but it is much harder to measure as a threat.

Brown is among the researchers at the Royal Botanic Gardens, Kew, in the London borough of Richmond, who have published these findings in a new report called State of the World's Plants and Fungi.

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