Examining how long it takes for new species collected in the field to eventually be identified, British researchers found it often took decades, the BBC reported.
Of the approximately 70,000 flowering plant species experts believe are yet to be found, over half may already be in collections awaiting identification, scientists say.
For hundreds of years, plants have been collected by mounting them on cardboard and placing them in what is known as a herbarium for safekeeping.
Robert Scotland of Oxford University and his colleagues decided to try and calculate how many undiscovered species of all flowering plants may be contained in such collections.
Of more than 3,200 species identified since 1970, they calculated that only 16 percent were described within five years of collection, while almost a quarter were described more than 50 years after they were first collected and placed in herbaria.
One species took 210 years to be identified, they said.
Scotland's study found 60 new species in herbaria collections.
"I was looking at those 60 species and what I noticed was that most of them were first collected by botanists over 60 years ago," he said. "I was quite surprised by that."
"Out of that 70,000 species still to be found, more than half of those have already been collected in the world herbaria and are waiting for someone with the relevant expertise and time to say 'that's a new one,'" Scotland said.
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