Approximately 380 000 plants are in risk of extinction worldwide.

Studies conducted by the Royal Botanic Gardens and the Natural History Museum, UK, in partnership with the International Union for Conservation of Nature (IUCN), about the risk of extinction of plants in the world found that up to one fifth of the species is threatened.

This is the first time that damage to approximately 380 000 known plant species worldwide are estimated. Results will be used for conservation work and are fundamental for UN meeting on Biodiversity to be held in Nagoya, Japan this month from 18th to 29th.

http://www.biodiversityislife.net/?q=Nagoya

The work was based on the files of the botanical garden with more than eight million species of plants and fungi preserved in more than six million species from the collection of data and digital collections of partner institutions.
The task of mapping the threat to more than 380,000 plant species estimated is a much bigger challenge than the same analysis of birds (10,027 species), mammals (5490 species) and amphibians (6,285 species). Therefore, a sample of 1,500 species was collected from each of the five largest groups of land plants: bryophytes, pteridophytes, gymnosperms, monocots and legumes. Both rare and common plants were selected.
Simulations done previously for amphibians and birds have shown that 1500 would be a sufficiently representative to draw the picture.
The conclusions are:

- About a third of the sample species are so little known that tests can’t be done on their conservation.

- Of more than 4000 species carefully analyzed, 22% (more than one fifth) were classified as Endangered.

- The plants are more threatened than birds, as equally as threatened mammals and less threatened than amphibians and corals.

- Gymnosperms (pine, pines, redwoods ...) are the group most threatened.

- Rain Forest is the most endangered habitat.

- The most threatened species are found in the tropics.

- The greatest threat is loss of habitat for humans, especially for agriculture and livestock.