Hoyt Arboretum Friends (HAF) is a membership-based, nonprofit organization working in partnership with Portland Parks and Recreation to support Hoyt Arboretum.

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About Our Collection


Hoyt Arboretum as a living collections museum plays an important role in serving the community in understanding biodiversity, conservation, education, and research. Hoyt is home to over 170 plant families and 2,068 species - 63 of which are listed globally vulnerable or endangered by the International Union for Conservation of Nature and Natural Resources (IUCN). As a member of Botanic Gardens Conservation International, we actively conduct ex situ conservation on our threatened species, while educating our regional and global audience about extinction and conservation issues.

As with any museum specimen, provenance of our collections begins with tracking wild collected seeds through arboretum planting and maturation. Species determination and vouchering is conducted at the time of flowering and fruiting. Provenance is expressed through vouchers and provides a permanent record of our collections.

Our publicly accessible IrisBG plant inventory has both Latin and common names. Through the plant inventory, users are able to pinpoint locations of individual arboretum trees. The database also provides botanical information including rarity status and country of origin. Our plant database partner is Leach Botanical Garden. Leach focuses on unusual and rare herbaceous species found in Oregon while the Hoyt Arboretum collection is global, making the collections successful compliments of each other.

The Hoyt Arboretum Herbarium is actively curated and open to the public. We are in the process of determining and vouchering all 6,000 trees in our collection as well as the 7,000 species at Leach Botanical Garden. Vouchers are priceless records, expressing provenance of our most valuable species. In addition to curating our arboretum collections, we serve as a specimen repository and provide determination services for a wide variety of community partners including Portland Parks & Recreation, the City of Portland Bureau of Environmental Services, Metro Regional Government, and university researchers and students. Our long-term partnership goals are to voucher rare and invasive species on all 8,000 acres of Portland Parks & Recreation natural areas including natural areas held by partner government entities.

Herbarium determination services, as well as all our teaching vouchers, are available to researchers, conservation biologists, restoration biologists and educators at all levels as well as the general public. For more information please contact our Arboretum Curator or Systematic Botanist.

Organization of Arboretum and Herbarium Collections

Both of our living tree collections and herbarium are arranged within an evolutionary construct using Angiosperm Phylogeny III Herbarium Sequence. This phylogeny-based organization of our collections reveals the evolutionary relationships among and between all species in our collections. This type of organization lends itself to multilayered educational opportunities and aids in research among systematic botanists, conservation biologists, and the general population.

The Bill deWeese Classroom in the Visitor Center houses our research library. Our library has over 800 books ranging from technical floras to beginner gardening books. The public is welcome to investigate our growing collection of research material. Please come peruse our library during Visitor Center hours.