American Elms

As we cross College Road, look ahead and you'll see an American elm, its elegant wineglass shape immediately distinguishable even in winter. This elm is a rare specimen; while elms used to line streets in towns all over America, an outbreak of Dutch Elm Disease in the 1930's wiped out nearly all of the species. The disease is a fungus, carried by the elm bark beetle, which blocks the vessels inside the tree from carrying water from the roots to the leaves. Without water, the leaves wither and eventually the tree dies. If diseased wood or roots come in contact with uninfected trees, the healthy trees will quickly become infected. Burning diseased wood is one way of halting the spread of the disease, and some experts can inject fungicides into the root systems of the trees, which is in some ways effective.

There is some hope for the American elm, however. The three saplings just beyond the old tree are a new disease-resistant variety of the species, so Wellesley may again become an elm-lined campus. Also, other species of elm, such as the Chinese elm, are naturally resistant to Dutch Elm Disease and grow in other parts of campus.

Off to our right is the Dower dormitory, which recalls Wellesley's more agricultural days; it is a converted horse barn! Right in front of it is a huge old hemlock, which unfortunately is also suffering from an infestation of the Hemlock Woolly Adelgid, a pest species that was accidentally introduced to North America. This aphid- like insect feeds on the sap of twigs eventually killing the twig and often the tree. Such infestations are extremely difficult to control, and the campus will likely lose quite a few hemlocks.

Let's continue straight along College Road, and then veer off to the right to explore a thriving ecosystem, the Wellesley meadows.