How it was done

Scientists, conservationists and volunteers from Kew, the Natural History Museum and the International Union for Conservation of Nature (IUCN) carried out the IUCN Sampled Red List Index assessments for plants in response to the United Nation's International Year of Biodiversity and the 2010 biodiversity target. The monocotyledons and legume groups were assessed by Kew and the pteridophytes were assessed by The Natural History Museum.

7,000 plant species drawn from the five major groups of plants were included in the study, as representative of the other flowering plants. Both common and rare species were assessed in order to give an accurate picture of how plants are faring around the world.

For these groups 1,500 species were selected at random and each assessed against the IUCN Red List Index categories and criteria. As there are fewer than 1,500 gymnosperms, all species in this group were included, using the existing assessments of the IUCN Conifer and the IUCN Cycad Specialist Groups, together with the new assessments for the remaining species (Gnetales).

The work relied heavily on the vast repository of botanical information held in Kew’s Herbarium, Library, Art and Archives, which includes some eight million preserved plant and fungal specimens; on specimens held in the Natural History Museum’s own extensive herbarium of six million specimens; on digital data from other sources and on collaboration with Kew’s network of partners worldwide.

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About the data

There are more than 380,000 species of plants known to science and even more yet to be discovered. With so many plant species in need of conservation assessment, how do we know if a plant species is threatened?

As the task of assessing the threat to the world’s plants (perhaps as many as 380,000 species) would present a much larger challenge than the assessments of threats to birds (9,998 species), mammals (4,000 species) or amphibians (6,433 species), a sampled approach was adopted where 1,500 species were randomly selected from each of the five major groups of land plants. Find out more about the plant groups included here.

Together with information about the species from botanical literature, from analysis using Geographical Information Systems (GIS), Google Earth and the expert opinion of scientists who know that species or the area of the world where it is found, it is possible to assess a species’ conservation status and assign threat ratings to most species of plants.

Scratch pad - collaborate with Kew

As assessments are completed they are posted up on the project scratchpad for comment and verification from international experts who are collaborating with us on this project.

If you are an expert or have specialist knowledge of any of the species covered by the project you can contribute your expertise, comment on our assessments or give us your feedback by adding content for these species to the scratchpad.

Please note that all assessments are pending approval by IUCN before appearing on the Red List Index website, unless otherwise stated.