Bringing back the American Elm to celebrate Durham’s 30th year as “Tree City USA”
In case you were wondering what those new trees are that have appeared up and down University Drive/Lakewood Avenue, wonder no longer. Those are American Elms.
Please bear with me a moment before berating me for selecting disease-prone trees for your streetscape. These trees are disease-resistant “cultivars” (cultivated-varieties) trademarked as “Princeton,” propagated from an individual tree from the town which bears its name. In its long life the tree never showed a hint of being affected by Dutch elm disease (DED) – though all its neighbors succumbed.
As urban shade trees go, the American elm’s history is interesting. All the characteristics that make for a great shade tree are present in this species, tall, strong, fast-growing, long-lived and adaptable.
Elms are an ancient race of tree; fossils appear in the tertiary rocks of Greenland, and in the Miocene period they flourished in a broad belt across America, Europe and western Asia. In the United States and Canada it had a very wide distribution, from Newfoundland to Saskatchewan, and from Florida to Texas.
It is one of the first trees to flower in early spring (in fact it’s flowering right now), but you have to know what you are looking at. These flowers are not conspicuous, being brown, small and high up in the canopy.
The canopy of the American elm was its most beloved trait. It is upwardly ascending and then it spreads out, high overhead into a “vase-shaped” form. The archetypal New England cathedral-ceiling streetscape is made up of these trees.
The story of this native species’ near disappearance and ultimate re-emergence in our urban areas is one of the rare happy endings from the growing list of native trees which have been impacted by imported pests and diseases.
Dutch Elm Disease came to America on board a load of elm logs from Europe, brought in to make furniture in Ohio in 1928. It originated in Asia, and was first identified in Europe in 1910. The causal agent was first isolated in 1921 by a Dutch researcher; thus the disease was forever (unfairly) associated with the Netherlands.
The disease is spread by the European elm bark beetle, which carries pathogenic fungi from tree to tree. Trees then spread it underground via root grafts, so eradication efforts targeting the beetles with DDT, didn’t work.
Sadly, European elms were initially only moderately affected by the disease. It took a reintroduction of a virulent American strain in 1967 to wreak the sort of havoc there that we experienced here, from its introduction through the 1970s.
In fact, the wholesale loss of elm trees in urban areas is said to have ushered in a new profession here in the U.S., that of “urban forester”.
Here in Durham we initially bypassed the American elm as a street tree. We were planting our street trees in the post-DED era and went with native oaks, and as a result we still have big, old oak trees around.
So enjoy your new trees! They came courtesy of a generous donation from BP/Family Fare, coordinated by local Durhamite Lee Barnes. The donation went to Keep Durham Beautiful and has been used to plant 50 trees in celebration of Durham’s 30th year as a “Tree City”. The real celebration is set to take place March 22 at 11 a.m. across from City Hall. Please attend if you can.
Resources used in this article: Wikipedia, and “Our Native Trees,” Harriet L. Keeler, Charles Scribner’s Sons, New York, 1917