About the Index

The records in IPNI come from three sources: the Index Kewensis (IK), the Gray Card Index (GCI) and the Australian Plant Names Index (APNI). Detailed information about these indices is available through the links above. This page summarises basic information about each data source and the procedures followed in merging the records so that the user can understand the origin and the limitations of the combined dataset. For more about the data limitations and the subsequent effects on search results, read our page on understanding the data.

The Data Sources

Geographical and historical coverage

Over one million records have come from Index Kewensis. This is global in coverage and lists names from the first edition of Linnaeus's Species Plantarum to those being published now. Basic bibliographic details are included for each name and for later records the year of publication is also included. Until 1971 infraspecific names were not included – while the Gray Index and the Australian Plant Names provide some of the infraspecific names which are lacking in IK but their coverage is not so extensive, so many names below species level are missing from IPNI. The current electronic version of the Index Kewensis was produced by an optical reading process in the mid 1980s. Despite careful checking of the scanned data, many errors were introduced into the Index at this time.

Over 350,000 records have come from the Gray Index (originally the Gray Herbarium Card Index) which includes names for New World taxa published on or after January 1886. Basic bibliographic details and date are included for each name and many records include information about types. The data were converted to electronic form in the early 1990s and much time has been invested in their standardization and verification since then. Although most of the citations in the Gray Index are for names also recorded in Index Kewensis, there are many records for New World infraspecific names which are unique to the Gray Index. The duplicate records are also of considerable value since they tend to be more detailed than the equivalent IK record and also because errors in either index can be detected by comparing records for the same name. Furthermore the Gray Index includes many records of typifications subsequent to the time of validation of a name (epi-, lecto- and neo-typifications) which are not duplicated elsewhere.

Over 63,000 records have come from the Australian Plant Names Index which has been compiled since 1973 and includes all scientific names used in the literature for Australian vascular plants. Levels of detail and validation are higher for this index than for the IK or the GI. Most names have been checked back to their original place of publication and type information is included for each name. APNI includes many names not included in the IK, especially of Australian infraspecific taxa, and, as in the case of the Gray Index, overlap in coverage between IK and APNI offers scope for checking data and eliminating errors.

Taxonomic coverage

Index Kewensis includes only the names of seed plants. Index Filicum, covering the ferns (and incorporating fern allies published after 1960), is now included as of 2004. The Gray Index names include vascular plants of the New World. The Australian Plant Name Index records names for all Australian plants but its contribution to IPNI is restricted to the flowering plants, the ferns and their allies.

Thus while there is considerable overlap in content between the three indices they are in many ways complementary. IPNI, the product of a merger between these three, represents the most comprehensive listing of plant names available today. A number of editorial processes are planned to improve the quality of the data over the coming years. These include deduplication, standardisation and verification.

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