THE LEAFLET

At the turn of the 20th century, American Elms were ubiquitous in urban landscapes across the United States. The tree was prized for its graceful vase-like shape and ability to create large, natural canopies over streets and sidewalks. Elms were also a desired species to plant due to their significance within American culture. Ever since colonists gathered around the Liberty Tree in Boston, the Elm has been a symbol of American independence, and planted all over the United States, including our nation’s capital.

However, the arrival of Dutch elm disease (DED) in the 1930s devastated elm populations nationwide. By the 1950s, the disease had reached DC, claiming over 200 trees on the National Mall by the mid-1990s.

It was at that time that James Sherald, working with the National Park Service’s Center for Urban Ecology, made a crucial observation. He noticed that certain elms on the National Mall had darker green leaves, more rounded crowns, and retained their fall foliage almost a month longer than their counterparts. This extended foliation period suggested a potentially healthier specimen, possibly resistant to DED.

One tree in particular caught Sherald’s eye. Growing near the Freer Gallery of Art on the National Mall since the 1930s, it was one of the original 300 American Elms planted on the National Mall at the time. This particular elm had survived unscathed while others succumbed to the disease. The tree, and others then propagated from it, would later become known as the Jefferson Elm.

In 2005, after years of testing and development, the National Park Service and the U.S. Department of Agriculture jointly released the Jefferson Elm cultivar to commercial nurseries. This release marked a significant milestone in the effort to reintroduce disease-resistant American Elms to the urban landscape. Today, Sherald’s work can be seen throughout Washington, DC and across the nation.

Current inventory of Elm species on the National Mall.

James Sherald passed away in the Fall of 2023. He worked for the National Park Service for over 35 years, served as a Casey Trees board member, and remained passionate about the Elm even in retirement, gathering seeds and propagating trees to share with family and friends. He left a lasting mark on the urban forestry field, and sparked joy and the love of trees for all.

James Sherald – known as Jim to his family and friends – was a dear friend of Casey Trees. Executive Director, Mark Buscaino, reflected on his legacy and what he meant to the organization:

James Sherald standing next to a Jefferson Elm on the National Mall.

“Since 2011, Jim served on Casey Trees’ board, but he was involved with us from the very start. He was a key advisor when Casey Trees inventoried DC’s street trees with an army of trained volunteers. When those volunteers were done, they in turn successfully advocated for the passage of significant and transformational tree protection laws that stand to this day.

As a plant pathologist, Jim was passionate about the American Elm. For decades scientists sought trees with resistance to DED – like trying to find a needle in a haystack. Jim succeeded when he discovered what is now known as the Jefferson Elm, now widely propagated and which Casey Trees has planted thousands throughout the DMV – each and every one a tribute to Jim’s persistence.

Casey Trees would not have been as successful as it has been without Jim’s guidance and professional insights. But perhaps what many who knew him best will remember most was his kind nature, always quick to share a story or comfort a friend wrestling with a challenge. Jim was a true professional, a true friend, and he will forever remain in our hearts and in the history of Casey Trees.”