25 October 2023

Kew’s oldest project celebrates 130 years

A direct result of a request from the most famous naturalist of all, it dates back to the 1880s – this is the story of the Kew International Plant Names Index.

A collection of Index Kewensis books dating from 1883 to the modern day

Many moons ago…

In the year the school leaving age was raised to 11 years old, Queen Victoria entered the 56th year of her reign and Dundee F.C. was formed, there was also a crucial scientific beginning: 1893 was the year Kew’s first comprehensive list of plant names was published – as Index Kewensis

The many spines of Index Kewensis issues
The spines of Index Kewensis tell a story spanning more than a century © Emma Wrankmore, RBG Kew

Crucial for conservation

This weighty tome was created in direct response to a request from Charles Darwin. On his death in 1882, he left Kew a legacy of ‘about £250 annually for 4 or 5 years, for the formation of a perfect M.S. catalogue of all known plants’.

Darwin was one of many scientific thinkers who realised the importance of having a list of plant names that can be shared globally. 

If scientists cannot name things accurately then how can we begin to know which plants are desperately in need of protection and which may hold the keys to protecting our planet?

A portrait photo of naturalist Charles Darwin and his signature
An original photo and signature from Charles Darwin

An impossible task?

You could be forgiven for thinking that such an ambitious project would be doomed to fail. The pioneering botanist, Daydon Jackson said the project would take six years, yet the first fascicle of Index Kewensis only came out in September 1893, 11 years later. 

This letter from Kew’s archives, sent by G. King to Sir William Thiselton-Dyer on 28 Feb 1893 demonstrates how much-needed this new plant list was considered to be.

“Index Kewensis is printed up to the letter F! I wish it was up to Z.  Its completion will vastly simplify the task of the Botanical monographer”

- G. King, 28 Feb 1893

A letter reads Index Kewensis is printed up to the letter F! I wish it was up to Z.  Its completion will vastly simplify the task of the Botanical monographer"
A letter from Kew's archives sent by G. King shows an appreciation for Index Kewensis from its inception. Archive ref: DC 156 f.887 © RBG Kew

The digital age

Despite the delays in producing the first printed copies, and the mammoth nature of the task, the project itself went on to flourish. Supplements and subsequent editions of Index Kewensis continued to be released until 1989.

The printed version of Index Kewensis was scanned and distributed via CD-ROM in the 1990s.

Kew’s Index Kewensis team formed a collaboration with Harvard University and The Australian National Herbarium in 2000 and together created the International Plant Names Index (IPNI). This included names from Index Kewensis, Harvard’s Gray Card Index and the Australian Plant Name Index, and meant that for the first time these names were available to all online.

Welcome to the International Plant Names Index (IPNI) is the text upon arrival on the IPNI site.
The homepage greeting of the IPNI database © RBG Kew

Free access for global users

More than 200,000 people per year use IPNI, with India, the United States, China and Brazil being among the top users. 

The database provides the essential names backbone for many taxonomic resources. These include Plants of the World Online (POWO), which includes images and distribution maps, and World Flora Online (WFO), created in response to the Global Strategy for Plant Conservation

IPNI's data feeds into the latest State of the World’s Plants and Fungi report and provides the names used to create crucial conservation checklists that help inform the decision-making of governments and other users. The World Checklist of Vascular Plants is one such list: a global resource of expert-reviewed taxonomic data connected to the web of plant names, completed recently after 35 years of work!

IPNI’s team of content editors add new names every day and deal with enquiries from researchers worldwide, amending existing entries where needed. This continual curation is part of what makes IPNI so valuable. 

E.woodii's influorescence appears as a massive pinecone shape.
Encephalartos woodii, Wood’s cycad, is Extinct in the Wild but one male plant grows at Kew. © RBG Kew

We need you!

You can now add vascular plant names that are missing from IPNI using our new registration system at https://ipni.org/registration/

Please also help improve this global resource by sending corrections to ipnifeedback@kew.org 

We are proud to be celebrating the 130th anniversary of this project which continues to support plant science and conservation at this critical time.

- The IPNI Team

P.princeps has huge ornate flowars. Long red petals spread in a star shape around a central reproductive area with large stamen and stigma
Passiflora princeps is a liana native to southeastern Brazil that thrives in wet, tropical biomes. © RBG Kew
Welcome to the International Plant Names Index (IPNI) is the text upon arrival on the IPNI site.

Global free access to IPNI

The world's plant names at your fingertips.

A forest landscape has light shining through gaps in the canopy. Leaf litter covers the floor.

The State of the World's Plants and Fungi Report

Read more about why names matter in the latest assessment of global plant and fungi diversity