The common daisy – Bellis perennis L – has 29 synonyns recorded, the Plant List has discovered. Picture: AFP/ Royal Botanic Gardens
Source: AFP

LIFE on Earth is less diverse than we have been led to believe, with a review of the world’s million named plants able to confirm only a third of them as unique.

The Royal Botanic Gardens at Kew, south west London, has updated a project conceived 130 years ago by Charles Darwin to identify every plant known to science.

But it found that the list, which was started in the 1880s with the help of a bequest from the great naturalist of 250 pounds a year for five years, was largely made up of repetitions. Hundreds of botanists thought that they had discovered new species but they were naming previously identified plants.

Kew, working with the Missouri Botanical Garden in the US, found that a sub-species of English Oak had been “discovered” 168 times. The Plant List, published online yesterday, also weeds out 51 synonyms for the common beech, 29 for the common daisy and 26 for the bluebell. The giant sequoia, native of Sierra Nevada in California, has been named 18 times by different botanists.

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By painstakingly comparing entries, Kew found 300,000 unique species and 480,000 synonyms of those species. Another 260,000 names are listed as “unresolved”, meaning that botanists have so far been unable to determine whether they are a separate species or a duplication of one of the 300,000.

Families of plants with the highest proportion of unresolved names include the umbellifers, such as carrot and celery, the cactus family and the solanaceae family, which includes the potato and tomato.

Kew found 17,844 different names for hawkweeds but decided that 8,000 of these were synonyms. It has so far identified 1,411 different species of hawkweed but says that it needs to do more work on another 8,000 names to determine whether they are unique.

Researchers at Kew said that the lack of a definitive list of all plants had held back conservation efforts and prevented institutions from sharing information on the same plant. By identifying the synonyms for each plant, the Kew study has enabled scientists anywhere in the world to gain access to all the research conducted into a particular species.

Conservation bodies are expected to use the list to focus their efforts on truly endangered species rather than wasting resources protecting plants that may be rare in one place but abundant in another. Kew reviewed the “Red List” of threatened plants of Botswana and found that six of the names listed there were actually synonyms of other plants that were not threatened.

The linking of different names for the same plant is also likely to help medical research. Mu Xiang, a plant widely used in traditional Chinese medicine, has five synonyms. Kew said that health regulators in different areas would now be able to share information on the remedy.

A Kew spokesman said: “Without accurate names, understanding and communication about global plant life would descend into inefficient chaos, costing vast sums of money and threatening lives in the case of plants used for food or medicine. The Plant List provides a way of linking the different scientific names used for a particular species together, thus meeting the needs of the conservation community by providing reliable names for all communication about plants and their uses.”

Eimear Nic Lughadha, the Kew scientist who led the Plant List project, said: “We can now pull all the information together on the same plant and plot on a map where it occurs. This enables us to decide quickly which species are most threatened.”

She said that the original list, funded by Darwin and published a century ago under the title Index Kewensis, had simply been a list of 400,000 names, with little effort to remove duplication. An average of 6,000 names had been added every year since it was first published, with many new names describing plants already listed. “It was difficult to cross-check before the internet existed. This [duplication] happens much less often now,” she added.