The Index Herbariorum provides a global directory of herbaria and their associated staff. This searchable online index allows scientists rapid access to data related to 3,400 locations where a total of 350 million botanical specimens are permanently housed (singular, herbarium; plural, herbaria). The Index Herbariorum has its own staff and website. Over time, six editions of the Index were published from 1952 to 1974. The Index became available on-line in 1997.
The index was originally published by the International Association for Plant Taxonomy, which sponsored the first six editions (1952–1974); subsequently the New York Botanical Garden took over the responsibility for the index. The Index provides the supporting institution's name (often a university, botanical garden, or not-for-profit organization), its city and state, and each herbarium's acronym, along with contact information for staff members and their research specialties, and the important holdings of each herbarium's collection.
- 6th edition (1974) was co-edited by Patricia Kern Holmgren, Director of the New York Botanical Garden
- 7th printed edition, ed. by Patricia Kern Holmgren.
- 8th printed edition, ed. by Patricia Kern Holmgren.
- Online edition, prepared by Noel Holmgren of the New York Botanical Garden
- 2008+, ed. by Barbara M. Thiers, Director of the New York Botanical Garden Herbarium 
- "Index Herbariorum". sweetgum.nybg.org. Retrieved 9 August 2017.