The Morton Arboretum announced today that Gerard T. Donnelly, Ph.D., will retire as president and CEO on September 30, 2022. Donnelly has served in his role since 1990.

“It has been my aim to elevate The Morton Arboretum and grow its capacity to champion the cause of trees in the world,” Donnelly said. “I have been fortunate to be able to lead this organization through a period of dramatic growth in its reach and impact at a time when its tree-focused mission is needed more than ever.”

Over the last three decades, Donnelly has increased the Arboretum’s visibility, public outreach and philanthropic support. As a trained botanist and forest ecologist, he has greatly expanded the organization’s science, conservation and education programs that are aligned with its world-renowned tree collections. The institution will celebrate its centennial year in 2022.

“The Arboretum’s success has been powered by its talented staff and dedicated volunteers, a passionate and encouraging board of trustees, and the enthusiasm and generosity of donors, members and the public through the years,” Donnelly said.

Donnelly led initiatives to redevelop the Arboretum into a more visible and welcoming destination, including the addition of a landmark four-acre Children’s Garden that draws new generations to explore trees and nature and become future stewards of the environment. Improvements to the 1,700-acre site led to increased public awareness, attendance and support, which have continued to grow and position the Arboretum among the Chicago region’s top visitor attractions and as the most-visited arboretum in the world. As the Arboretum prepares to enter its second century, 60,000 member households support its mission and one million guests visit each year.

Through Donnelly’s leadership, the Arboretum has led significant collaborations to plant and study trees. He was instrumental in the establishment of the Chicago Region Trees Initiative, a coalition that now includes 200 organizations working to improve the health of the regional forest. Donnelly founded ArbNet, an international community of arboreta working to advance the purposes of tree-focused public gardens, and the only accreditation program specific to arboreta.

Donnelly also led the formation of The Center for Tree Science, bringing together researchers to develop scientific knowledge and technical expertise to address the key challenges facing trees. The Global Tree Conservation Program was developed under his leadership to prevent the extinction of priority threatened tree species in biodiversity hotspots around the world.

Further, Donnelly has provided leadership in a number of key roles within the botanical profession regionally, nationally and internationally. He serves on the board of Botanic Gardens Conservation International and chairs its International Advisory Council, has chaired the board of the American Public Gardens Association and has for years coordinated the Directors of Large Gardens network of the major botanical gardens and arboreta in North America.

“Thanks to Gerry’s exceptional leadership and talent, The Morton Arboretum has grown to become the leading arboretum in the world, as well as a tremendous asset for our community,” said Stephen C. Van Arsdell, chair of the Arboretum’s Board of Trustees. “As a scientist and innovator, Gerry has positioned the organization for continued success into its second century as a center of tree expertise and source of inspiration for people to plant and protect trees.”

Donnelly recently guided the development of the Arboretum’s Strategic Plan 2020+ focused on trees, climate, sustainability and inclusion. He also spearheaded the vision and fundraising for The Grand Garden, a major new feature and central attraction at the Arboretum, and a centerpiece of the centennial year celebration. The Grand Garden will open in September of 2022.

The organization’s Board of Trustees has established a leadership transition committee to facilitate the search for Donnelly’s successor. Koya Partners in Chicago, an executive recruiting firm that specializes in mission-driven search, has been retained to conduct the search.

About The Morton Arboretum

The Morton Arboretum is an internationally recognized tree-focused botanical garden and research center near Chicago in Lisle, Illinois. The Arboretum ranks among the leading arboreta of the world in size, age, quality of specimens, and programs and initiatives to plant and protect trees. Established in 1922 by Mr. Joy Morton, founder of the Morton Salt Company, the Arboretum encompasses 1,700 acres of plant collections and gardens amid natural landscapes of woodlands, prairie, lakes and streams. The mission of The Morton Arboretum is to plant and protect trees for a greener, healthier and more beautiful world. Information about exhibitions, events and admission is available at