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How to Cite Index Herbariorum
Index Herbariorum (updated continuously). Index Herbariorum: A Global Directory of Public Herbaria and Associated Staff. New York Botanical Garden. Published online: https://sweetgum.nybg.org/science/ih/ (accessed DATE).
History
For the past three centuries, scientists have documented Earth’s plant and fungal diversity through dried reference specimens maintained in collections known as herbaria. As of December 31, 2025, there are 4,035 active herbaria worldwide, with approximately 13,625 associated staff persons. Collectively, the world’s herbaria contain an estimated 406,426,591 specimens documenting the planet’s vegetation over the past 400 years. Index Herbariorum is a guide to this crucial resource for biodiversity science and conservation.
The Index Herbariorum (IH) entry for an herbarium includes its physical location, URL, contents (e.g., number and type of specimens), founding date, as well as names, contact information, and areas of expertise of associated staff. Only collections that are permanent scientific repositories are included in IH. Each institution is assigned a permanent unique identifier in the form of a one- to six-letter code, a practice that dates to the founding of IH in 1935.
The first six editions of Index Herbariorum were published by the International Association for Plant Taxonomy in the Netherlands (1952–1974). Dr. Patricia Holmgren, then Director of the New York Botanical Garden’s William and Lynda Steere Herbarium (NY), served as co-editor of edition 6 and subsequently became senior editor of IH. She oversaw the compilation of hard copy volumes 7 and 8, and Dr. Noel Holmgren, a scientist on the NYBG staff, oversaw the development of the IH database, which became available online in 1997. In September 2008, Dr. Barbara M. Thiers, subsequent Director of NY, became Editor of IH. In 2026, editorship of IH transitioned to an editorial team comprised of NY staff.
A 2016 grant from the U.S. National Science Foundation (DBI grant #1600051) supported major enhancements to Index Herbariorum. With this funding, the Biodiversity Information Management team at the New York Botanical Garden expanded the database to include additional information about herbarium collections (e.g., specimen counts by major groups), the status of collection digitization, and the data portals through which specimen data can be accessed. An API was also developed to facilitate integration of IH data into other applications. The update procedure for Index Herbariorum was also modernized to allow herbaria to update their own information and register new collections directly through an online editorial platform.
All updates and new registrations of herbaria and associate staff are reviewed by the Editor and are not published online until approved.