U.S. National Arboretum Herbarium

herbarium voucher for Rhododendron 'Bacchante'

What is an Herbarium?

An herbarium (plural: herbaria) is a collection of preserved plant specimens used for scientific research. It is similar to a library filled with primary sources, providing scientists with hands-on access to plant materials. Herbarium specimens are necessary for studies in taxonomy, ethnobotany, ecology, phylogenetics, biogeography, and many other fields.


The United States Department of Agriculture (USDA) has maintained an herbarium on and off since 1868. The present herbarium of the U.S. National Arboretum was established in 1934 and was located at various sites until coming to the Arboretum in 1959. Today it is stored on two levels of the Administration Building on the Arboretum’s grounds.

The U.S. National Arboretum Herbarium Today

The U.S. National Arboretum Herbarium’s holdings number around 800,000 specimens, approximately 25% of which are from cultivated, rather than wild, plants. This emphasis on cultivated plants makes the herbarium here unique; it is one of the largest such collections in the world.

Dr. Svoboda with specimens in the herbarium

Among the important specimens housed here are germplasm vouchers, material from USDA-sponsored expeditions, documentation of plant invasions, and collections of notable botanical explorers. The herbarium also has around 1500 type specimens (those upon which the description and name of a new species is based) and over 2000 cultivated nomenclatural standards (authentic material to which a cultivar name is attached). Staff and interns at the Arboretum have been working to digitize these important specimens, and an ever-increasing number of them will be available on the JSTOR Global Plants database.

The Arboretum also houses the U.S. National Seed Herbarium, stored separately from the regular herbarium. This collection of approximately 140,000 vials and packets of preserved seeds is used mostly by botanists with the USDA’s Animal and Plant Health Inspection Service (APHIS) to identify foreign seeds that may enter our country.

For access to these materials or to schedule a tour of the collections, contact the Curator.

Contact Information

Dr. Harlan Svoboda, Curator
3501 New York Avenue, NE
Washington, D.C. 20002