Saturday, July 4, 2009

Ode to the Elm – a Fourth of July Tribute to an American Icon

I am easily impressed, I admit it. Still, the sight of a mature American Elm (Ulmus Americana) can send me into transports of delight. This stately tree, once ubiquitous east of the Rockies and synonymous with street side plantings, was nearly exterminated by the 1970s thanks to the fast work of an invasive insect and its associated fungus.

This pathogenic pair lived harmlessly in Asia, where the native elms were resistant to the effects of the fungus (Graphium ulmi). Somehow they made their way to the Netherlands, where in short order they did in the elms that held that country’s famous dykes (and hence the disease was named Dutch Elm Disease, or DED). From there DED migrated to England, taking out the stately English elms. Still, the US was protected; we were an ocean away and all ports of entry were watched and imported woods were thoroughly inspected. Or so we thought.

Suddenly in 1930 an outbreak occurred in Ohio. The “sanitary forces” were called in and the outbreak was eliminated. But in 1933, 3800 diseased elms appeared in New Jersey, and another 23 in Connecticut. The DED sleuths fanned out and the source was finally located: a load of English elm veneer wood, swarming with Scolytus multistriatus, the elm bark beetle. Forty years later, millions of elms across the US had succumbed to the disease.

Here’s what happens. The beetle (there is a native elm bark beetle as well as the invasive Asian species; both are now known to be carriers) snacks on the tree, chewing through the bark at the crotches of the twigs. Through these wounds the fungus’s spores, carried by the beetle, enter the tree. Once in the inner bark, they germinate, spreading fungal threads throughout the tree’s vascular system, essentially clogging it and preventing the transport of water and nutrients. Before long, the tree dies.

Mature trees were hit first, but folks were hopeful because seedlings and saplings were plentiful. Unfortunately, once saplings reached 4” dbh (diameter breast height, a measurement taken at 4.5’ above ground), they succumbed as well. So how is it possible that today I find mature trees?

It turns out that there were isolated pockets of mature trees that were never exposed to the disease, and other individuals exhibited resistance (a benefit of sexual reproduction). Today you can purchase varieties of resistant elms, such as “Valley Forge” and “New Harmony,” from various nurseries and breeders.

But what I enjoy is finding that lone wild elm, with its classic vase-shaped form. We have one here in Newcomb, prominently located at the Memorial Garden by the town’s Scenic Overlook. It is a breathtaking sight, this tall, graceful tree. Sadly, few people who see it probably realize what it is. Now that elms are few and far between, the specter of Dutch Elm Disease has been relegated to the halls of learning, where forestry and horticulture majors are about the only ones who learn of it.

This hit home for me about ten years ago when I worked at a zoo that had a magnificent specimen in one of its enclosures. No one else knew what it was and one day they decided to cut it down so they could expand the exhibit. I had to step in, crying “NO! It’s an elm – they are almost extinct!” It had a stay of execution that day, but by now it may be gone.

When American elms were plentiful, they played an important role in our history. Famous speeches were made under elms; treaties were signed; states were formed. So many historical events have been associated with elms that Donald Peattie wrote in A Natural History of Trees of Eastern and Central North America:

“If you want to be recalled for something that you do, you will be well advised to do it under an Elm – a great Elm, for such a tree outlives the generations of men…”

Elms can grow to over 100 feet in height, with diameters exceeding four feet and crowns stretching up to 150 feet! If it avoids DED (or elm yellows, the other major disease that affects elms), it can live for several hundred years. In the classic form the tree resembles a fountain: the lower trunk exhibiting no branches, then suddenly splitting into multiple stems from which the branches fan upwards and outwards. This arching, vase-like form made it the perfect street tree, for its branches would meet those of the elm across the street, uniting over the pavement and shading the cars below in a tunnel of green. Likewise, it was perfect for planting in the yard: no lower branches would hit you in the face for all the branches were up high, reaching over your house to cool it in the heat of the summer with its dappled shade.

Sure, there were some folks with a utilitarian eye who claimed the tree was useless. C.A. Sheffield wrote in the Atlantic Monthly in 1948:

“They are the most useless piece of vegetation in our forests. They cannot be used for firewood because they cannot be split. The wood cannot be burned because it is full of water. It cannot be used for posts because it rots in a short time. It can be sawed into lumber but it warps and twists into corkscrews and gives the building where it is used an unpleasant odor for years.”

Yet despite this, the American elm (aka: white elm and water elm) was plenty useful. Early settlers learned from the Natives that the bark could be easily stripped and made into cordage, baskets, and even canoes. Whips were made from the braided bark to urge recalcitrant oxen to their duties. Because the wood is so strong, supple, and shock resistant, it was ideal for the hubs of wagons used to carry heavy loads. It was also used to make agricultural tools, sporting goods, flooring, and was even used in ship building. Barrel staves and chopping bowls were routinely made from its wood. And, because it held screws better than any other wood, it was ideal for making boxes and crates.

Young elms can be found where mature elms once lived. I have an elm sapling that reaches into my yard. Learning to identify the asymmetrically heart-shaped and toothed leaf, with its sandpapery texture, is fairly easy. Scope out places where historic elms once grew (like The Elm Tree Inn in Keene), and you will likely find some youngsters growing quietly nearby. If you want to add an elm to your yard, then hop on-line and do a search for nurseries and breeders who have resistant varieties for sale. Every home should have an elm grace to grace its yard…and maybe a revival in street trees will take root, restoring the elm to its coveted place in our towns and cities.


Ellen Rathbone

Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.



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