Three in four undescribed plant species are threatened with extinction

Abstract Many thousands of plant species remain unknown to science, most being range-restricted and/or rare – both factors that increase extinction risk. Here, we show that more than 75% of species described after 2020 would qualify as threatened if assessed for the IUCN Red List. We recommend that newly described species are assumed to be threatened and encourage taxonomists to partner with assessors at the time of description to formally evaluate the extinction risk of new species using the IUCN Red List Categories and Criteria.