endanger plants species are under threat.

the researchers assessed a total of 7,000 plants species — including bryophytes (mosses and liverworts) and legumes (peas and beans) — from the five major plant groups. Examining more than 1 million herbarium specimens, the researchers looked at when and where a specimen was picked. This information was then fed into a computer-based geographical information system to produce a map of the different locations, or distribution, of the species worldwide, and also the size of the area or areas that they cover. Other information, such as habitat loss, collected from scientific literature and expert consultation, was also fed into the system to show whether the areas inhabited by particular species are under threat.

The study uses IUCN criteria to classify species as threatened. For example, a species is classified as 'critically endangered' if the area that it occupies covers less than 10 square kilometres and if the species is known to exist at only a single location.
The researchers plan to reassess the threat status to plants in 2015. Using the data published today as a baseline, they will be able to gauge whether the risk to plants is growing with time.
Stephen Hopper, director of the Royal Botanic Gardens, says that the assessment will help countries to measure progress towards new targets to halt loss of the world's biodiversity by 2020, which are due to be agreed when the countries that are signatories to the Convention on Biological Diversity meet in Nagoya, Japan, in October.
"The 2020 biodiversity target that will be discussed in Nagoya is ambitious, but in a time of increasing loss of biodiversity it is entirely appropriate to scale up our efforts," says Hooper. "We need a renewed commitment to care for biodiversity."