A new study found that 571 plant species have disappeared - four times more than the current listing of extinct plants.
Scientists at the Royal Botanic Gardens, Kew, and Stockholm University discovered plant extinction is happening up to 500 times faster than "natural" background rates of extinction - the normal rate of loss in earth's history before human intervention.
Dr Aelys M Humphreys, assistant professor at the Department of Ecology, Environment and Plant Sciences at Stockholm University, said: "Most people can name a mammal or bird that has become extinct in recent centuries, but few can name an extinct plant.
"This study is the first time we have an overview of what plants have already become extinct, where they have disappeared from, and how quickly this is happening."
Dr Eimear Nic Lughadha, co-author and conservation scientist at Royal Botanic Gardens, Kew, said: "Plants underpin all life on earth, they provide the oxygen we breathe and the food we eat, as well as making up the backbone of the world's ecosystems - so plant extinction is bad news for all species."
The research, published in the journal Nature, Ecology & Evolution, brought together data from fieldwork, literature and herbarium specimens.
The scientists found the highest rates of plant extinction to be on islands, in the tropics and in areas with a Mediterranean climate.
The research suggested the increase in plant extinction rates could be due to the same factors that are documented as threats to many surviving plants - change of land use and destruction of native vegetation, particularly range-restricted species.
Plants species which have disappeared include the Chile sandalwood, a tree that grew on the Juan Fernandez Islands between Chile and Easter Island, and was heavily exploited for its scent.
Another is the St Helena olive, first discovered in 1805 on the island of St Helena in the South Atlantic.
One lone elderly tree survived until 1994 and two more were propagated from cuttings, but they succumbed to a termite attack and fungal infections in 2003.