Nearly 800 plant species have disappeared since the 18th century, while thousands more are considered functionally extinct — no longer playing a role in their environment, or are so rare they are no longer able to reproduce.
Scientists at the Royal Botanic Gardens, Kew in the United Kingdom estimate undocumented extinctions could put the number much higher.
"Most plant extinctions happen silently,” with plant populations vanishing without people noticing until the absence starts to take its toll on nature, said Eimear Nic Lughadha, a conservation researcher at Kew.