Index Kewensis

The Index Kewensis (IK), maintained by the Royal Botanic Gardens, Kew, is a publication that aims to register all botanical names for seed plants at the rank of species and genera. It later came to include names of taxonomic families and ranks below that of species.

The Index is currently maintained as part of the International Plant Names Index in combination with the Gray Herbarium and Australian Plant Name indexes. This database is anticipated to complete the task of creating a complete list of plant names, although it does not determine which are accepted species names.

The preparation for this venture was made by Benjamin Daydon Jackson of the Linnaean Society, directed by Joseph Dalton Hooker at Kew. Charles Darwin provided the funding for the indexing project. When he died in 1882 his will stipulated that provision be made for £250 per annum over a 5-year period. In providing citations of plant names, the starting point was taken from 1753 onward; the year of publication for the Systema Naturae of Linnaeus. Darwin had found difficulties in applying these to the plants he studied, and Hooker's directive was to ‘the compilation of an Index to the Names and Authorities of all known flowering plants and their countries’. While the Index has never fulfilled this original charter, it was the most comprehensive for over 100 years.

Previous attempts at a comprehensive index had relied on secondary sources, this was the first attempt to provide the original publication details of the names. A note on the country of origin was also included. The publications of De Candolle, Pfeiffer, and Bentham provided models for the acceptance of names. However, the editor admitted that not all earlier sources were included; this sometimes led to subsequent errors in botanical nomenclature.

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