American Elm, English Elm, Chinese Elm, Zelkova, and Common Hackberry
The American elm is the tree that defines Harvard Yard. Its presence in the Yard likely dates back to around the founding of the University in 1636. But its status has taken a big hit with the coming of Dutch elm disease (see histoy section for more details). From a near monoculture, the numbers of American elms have dwindled significantly in the Yard. The American elm can be distinguished from other elms by its vase-like form. The main branches seperate from the trunk, then arch their way back towards the ground. As the bark ages, it also develops diamond-shape ridges.
The American elm not only has significant importance in the history of Harvard Yard, but also that of our great nation. It is the state tree of Massachusetts, but it has an extremely large range which extends across the great plains, to the south, and up to New England. In virtually any forest in any part of eastern North America, one should be able to STILL find this tree. It likes moist valleys and bottomlands, and despite Dutch elm disease, it still survives to some respect in the wild. The disease does not affect the trees until they are past reproductive maturity, so good size specimens can still be found.
There, however, is still hope for the rise of the American elm again. A disease resistant cultivar of American elm called the liberty elm is now being widely planted here in the US. Two of these trees were planted in the Yard last November near the John Harvard statue. These trees are American elms, not hybrids from European and Chinese species. Trees that survived fungus exposure were idnetified over the past 50 years and the result is the production of an American elm that can survive to replace its fallen ancestors.
This summer I read the book A Natural History of Trees of Eastern and Central North America by Donald Culross Peattie. He wrote, "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; the burning issues of today are the ashes of tomorrow, but a noble Elm is a verity that does not change with time. And though Elms too are mortal, great ones are remembered as long after they are gone as are great men."
An elm like this is found in Cambridge Common. The Washington Elm is the site where George Washington supposedly took command of the Continental Army. The original tree died in the 1920s, but a replacement tree is still there. Trees like this are found all over the country, where events of either local or national significance are marked by an American Elm.
An American elm in the Yard with Stoughton Hall (left) and Holworthy Hall (right) in the background.
Branches on the American elm gracefully hang on the tree. American elms by far have the best form of any decidious tree in the Yard.
Summer of 2004, another American elm meets its end.
There are two other types of elm in the yard, one of which is the English elm. This species does not have the vase-like form of its American counterpart. Its bark is marked by deep ridges and circular nodes or "burls", from which many shoots protrude. Harvard prunes these trees annually to remove these from the major branches.
The interesting thing about the burls on the English elm is that these help to make some interesting patterns on veneer wood. For this reason, logs from English elms were being imported into America in the early part of the 20th century. It was on shipments of these logs that Dutch elm disease first made it into this country.
The English elm form is different from that of the American elm. If you look closely, you can also see the round nodes on the main branches of the trunk.
The last elm in the Yard is the Chinese elm. This tree is much different from the first two I mentioned. This one has small leaves and bark that peels off to reveal a red-orange inner-bark. This tree is resistant to Dutch elm disease, and its form has lower branches swoop like the American elm.
This Chinese elm is located on the east side of Thayer Hall.
These trees guard Thayer Hall.
Chinese elm leaves.
One tree that has been brought into replace the American elm the the Japanese Zelkova tree. I, quite frankly, don't like this tree very much. It has a very cone-shaped form, which some say make it a good replacement for the American elm. However, it often suffers from branch dieback, which makes it rather unsightly. There are many of these trees planted along the Charles River along the basin.
The zelkova leaves are very similar to the elm.
I do need to mention another tree in this section that is not a true elm, but is a member of the Elm Family (Ulmaceae). This tree is the common hackberry. Its native setting is in eastern North America in moist valleys and river bottoms. It has many similarities to the American elm, including tall, thin, spreading branches. Its bark is very distinctive, with thin, vertical wart-like ridges. this makes it a very easy tree to identify any time of year.
The bark of the hackberry.
A grove of hackberry trees stand in front of Emerson Hall. The textured bark can even be seen in this low resolution image.
Created by Ryan Lynch
Map template courtesy the Harvard Planning and Allston Initiative
Last updated May 28, 2007