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Editor's Picks

Past IOS President Allen Coombes, Curator of Scientific Collections at Puebla University Botanic Garden, discusses leaf variability in Quercus ceirpes (still image from the documentary)
A new documentary by Maricela Rodríguez Acosta
Website Editor | Feb 17, 2026
Quercus miyagii acorn and dried leaves
A rare oak endemic to the Ryukyu Islands of Japan
Elion Jam | Feb 16, 2026
A moss-covered oak (Quercus orocantabrica) in Mata de Albergaria, Peneda-Gerês National Park, Portugal  © Amit Zoran
Steve Potter reviews a new book that features oaks
Steve Potter | Feb 11, 2026

Plant Focus

Quercus canariensis in Cornwall Park, Epsom, Auckland, New Zealand, the champion specimen in New Zealand, planted in the 1920s, 27.2 m tall with a trunk diameter of 209 cm (G. Collett pers. comm. 2026)  © Gerald Collett
Antonio Lambe shares his views on this threatened oak native to Iberia and North Africa

An International Accreditation Program for Arboreta

arbnet1ArbNet is an interactive community of arboreta, sponsored and coordinated by The Morton Arboretum in cooperation with the American Public Gardens Association and Botanic Gardens Conservation International. Its Arboretum Accreditation Program recognizes arboreta at various levels of development and capacity, based on an arboretum’s collections and curation, education and public programming, scientific research and conservation initiatives, governance, and staff or volunteer support.

The network was created to facilitate the sharing of knowledge, experience, and other resources to help arboreta meet their institutional goals and to help raise professional standards. Through ArbNet, arboreta from around the globe can work collaboratively as part of a broad network to help advance the planting and conservation of trees. The accreditation program offers four levels of accreditation, recognizing arboreta of various degrees of development, capacity, and professionalism. Accreditation is based on self-assessment and documentation of an arboretum’s level of achievement of accreditation standards. Standards include planning, governance, labeling of species, staff or volunteer support, public access and programming, tree science, planting, and conservation. These standards, and indeed the entire concept of ArbNet (which includes the registry, the website, and the accreditation program), were established to overcome the lack of definitions, guidelines, and an identifiable network specifically geared to arboreta.  

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Aerial view of Arboretum Wespelaar, Belgium (Level IV accredited arboretum)

The program provides guidance based on best practices, as well as tools to help organizations pursue and achieve accreditation. Any arboretum or other types of public gardens with a substantial focus on woody plants is eligible to apply for accreditation through the program. Examples of institutions that can qualify include botanical gardens, cemeteries, zoos, city tree collections, historic properties, college campuses, corporate campuses, nursing homes, nature reserves, and municipal parks.

Another driving force behind ArbNet, for the good of the overall arboreta community, is for the larger, well-resourced arboreta to provide guidelines, models, expertise, and inspiration for smaller arboreta, so that the entire network is stronger, more connected, and together is advancing the quality and capacity of tree-focused gardens. It is for that reason that it is so important to have large gardens as part of the accreditation program, so that they can provide leadership and guidance to the broader community. ArbNet uses many of the programs, documents (e.g., collections policies), and publications of level III and IV arboreta as resources for smaller arboreta to adopt and learn from. It is a valuable way for a higher level arboretum to exert leadership and influence.

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The Oak Islands at Taltree Arboretum in Indiana, USA (Level III accredited arboretum)

Among its achievements in its first six years, ArbNet has built capacity for smaller gardens and non-traditional arboreta like cemeteries, municipalities, and retirement communities. These organizations are tapping into audiences that traditional gardens don’t always readily access, broadening public awareness of the importance of trees and increasing the quality of curation of living tree collections.

The strength of the ArbNet network is its diversity – from major leading arboreta to lesser known but earnest gardens. By sharing perspectives and experiences, the network aims to build capacity, collaboration, and best practices for tree-focused gardens around the world.

As of July 2017, ArbNet has accredited 186 arboreta in 13 countries, including 19 arboreta with strong connections to IOS members (see a list of them here). If you have a documented collection of oaks or other plants, you should consider applying—it’s free!

More information is available at www.arbnet.org.