The new species were found in numerous countries and nearly a third are believed to be in danger of extinction.
Kew director Professor Stephen Hopper said: " It is not widely known that 2,000 new plant species are discovered worldwide each year. Kew’s botanists make a very significant contribution to this total. These new discoveries highlight the fact that there is so much of the plant world yet to be discovered and documented. Without knowing what’s out there and where it occurs, we have no scientific basis for effective conservation. It is vital that these areas of botanical science are adequately funded and supported."
Kew is currently working in partnership with 100 countries throughout the world. A full list of the 290 discoveries, together with selected profiles and an interactive map are also available.
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