Housed in the Bill deWeese Library at the Visitor Center, the Hoyt Arboretum Herbarium (HAH) is a museum of pressed and dried specimens comprised mainly of plants from the Arboretum.

The herbarium’s primary focus is to document and verify the arboretum’s internationally-renowned tree collection, adding scientific credibility and validity to the collection. Our continually-expanding herbarium also contains regionally significant plants from the Portland area.

The herbarium additionally functions as a reference library for City of Portland staff and partners, especially in the identification of street trees and invasive weeds. Started in 2008 and officially recognized in Index Herbariorum in 2012, the herbarium’s collections currently number over 3,000 specimens, with several hundred specimens added annually.

What questions can be answered from herbarium specimens?

Herbarium specimens form the basis for much of the information published in local floras and guidebooks. Specimens are frequently used to:

  • Verify a plant to species
  • Record floristic diversity for a given area
  • Communicate historic conditions to inform ecological restoration and conservation efforts
  • Serve as a source of plant genetic material
  • Track shifts in a plant species’ range over time
  • Inform public policies on species protection
  • Document changes in plant phenology due to shifting climate and environmental conditions

What references do we use to identify plants?

Most of the trees in the Arboretum are of known provenance, indicating that we have good documentation of where they came from. Many trees and plants at Hoyt Arboretum, however, are wild-collected from their native ranges, and require taxonomic verification. Click here to explore the resources we use to verify wild-collected species.


Services Provided

The Herbarium may provide plant identification services to City of Portland staff and partner agencies and organizations. This service is not available to the general public or for-profit entities. Contact the Herbarium Curator Mandy Tu for further information.


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