Firstly, our eternal gratitude goes to Charles Darwin, who left a legacy in his will in 1882 to fund ‘a perfect M.S. catalogue of all known plants’ which became Index Kewensis. To the librarian Josephine A. Clark at the USDA who compiled a list of names of plants from North America published in 1892 which led to the Grey Card Index. And to Nancy Burbidge who was instrumental in bringing about the Australian Plant Names Index. It is only through the hard work and generosity of visionaries such as these that IPNI has allowed to become the most complete source of plant names used by scientists around the world.

The IPNI team relies on support and advice from a large number of staff and research associates at the three partner institutions. These include:

At the Royal Botanic Gardens, Kew: Jen Alsop, Ken Bailey, Jeremy Bayliss, Fiona Bradley, Des Bennett, Diane Bridson, Neil Brummitt, Richard Brummitt, Simon Dixon, Keith Ferguson, John Flanagan, David Goyder, Mark Jackson, Bill Loader, Eve Lucas, Derek Martindale, Alison Mitchell, Anne Morley-Smith, Simon Owens, Ghillean Prance, Alyson Prior, Karen Smith, Matt Taylor, Mala Tu, Louise Vardey & Jeff Wheatley.

At Harvard University: Rose Balan, Michael Bartley, Lisa de Cesare, Helen Flagg, Maureen Kerwin, Antony Kirchgessner, Walter T. Kittredge, Kristin McDonnell, Gustavo Romero, Elizabeth A. Shaw, Leila M. Schultz, Judy Warnement, Timothy Whitfeld, Lenore Winkler & Emily Wood.

At the Centre for Plant Biodiversity Research, Canberra: Laurie Adams, Bill Barker, Arthur Chapman, John Hoskings, Terena Lally, Brendan Lepschi, Andrew Lyne, Tony Orchard, Julie Paul, Chris Puttock, Tony Rosling, Noel Vanspall & Annette Wilson.

The Australian National Herbarium also wishes to acknowledge the Australian Department of Environment and Heritage, CSIRO Plant Industry, the Council of Heads of Australian Herbaria and the members of the Herbarium Information Systems Committee, the Australian Biological Resourses Study.

The Plant Names Project (PNP) team extends special thanks to Bil Alverson, Jim Beach, David E. Boufford, Stan Blum, Noel Cross, Sally Hinchcliffe and Sylvie Jami for their invaluable support and practical assistance when the project was still in its infancy.

The Index Filicum records are available thanks to the tremendous efforts of Peter Bostock, Jim Croft, Peter Edwards and Bob Johns. Many thanks also to Patricia Holmgren (NY), Dan H. Nicolson (US), John Pruski (MO), Richard Rabeler (MICH), John Strother (UC) and Tom Zanoni (NY) for their significant contributions to the enhancement of the GCI.

In addition we are most grateful to the many botanists, biologists, computer programmers and information specialists who have contributed to the development of IPNI by giving us the benefit of their experience in a variety of forms ranging from constructive criticism and stimulating discussion through energetic enthusiasm to healthy scepticism: Bob Allkin, Randy Bellew, Walter Berendsohn, Frank Bisby, Alex Chapman, Bob Cook, Mike Donoghue, Werner Greuter, Gregor Hagedorn, Paul Kirk, John McNeill, Donald H. Pfister, Peter Raven, Jim Reveal, Peter F. Stevens, Charles Stirton, Piers Trehane, Richard White and Peter Winfield.

We would like to thank all those who have assisted us in the enormous task of merging the datasets by adopting a family. The following botanists contributed by linking equivalent IK and Gray Index records for particular families and genera: Marta Camargo Assis, José Fernando Baumgratz, André Carvalho, Inês Cordeiro, Andrew Doran, Rosângela Simão-Bianchini, Rafaela Forzza, Elaine (HUEFS), Nilda Marquete Ferreira de Silva, Efigênia França, Flávio França, Paul Goetghebur, David Goyder, Erika Guimaraes, Ray Harley, Indiara & Kelly (HUEFS), Candida Mamede, Renato de Mello-Silva, Lara Parra, Fabiana Pinto Gomes, Solange Pessoa, Sheila Profice, Alessandro Rapini, Cassio van den Berg and Hilda Longhi Wagner.

Finally, we would like to thank the users who continue to provide feedback that improves the data.

Core funding for IPNI is provided by the Royal Botanic Gardens.