Jeff Green | Apr 27, 2006
Back toHomeNature Reflections - April 27, 2006
by Jean Griffin
Before the leaves unfold on the deciduous trees, stop and look at the shape and outline of them. One of the most graceful of trees is the American Elm. With a tall, straight trunk and arching branches that may start high when among other trees, or when in the open with a trunk that divides into several limbs spreading out into a broad, fan-shaped crown, this is a beautiful tree. The lower limbs and small branchlets droop which can help separate from its cousin the Slippery Elm. Unfortunately Dutch Elm Disease has decimated many of our elms, and what we are left with is the stark outline of a dead or dying tree.
Dutch Elm Disease arrived in North America in the first half of the last century, brought to this continent in infected logs. There are two aspects of the disease. The fatal one is a fungus that clogs the vessels that transport water within the trees, resulting in wilting of the leaves and the appearance of yellow among them. Left to itself this fungus would probably not spread to any degree, but it has a carrier. Both native and non-native Elm Bark Beetles fly from tree to tree depositing their eggs and in the process carry with them the spores of the fungus. The result - devastation for thousands and thousands of elms.
Yet a few remain and their vase-shaped or umbrella-shaped outline can still be seen against the skyline. Found in Canada from western Newfoundland to Saskatchewan , an American Elm, if it has escaped the disease, could reach a height of 35 m and live up to 300 years. And in April or May as you look at them, these trees will be in bloom. Before the leaves appear special flower buds open to display inconspicuous bisexual flowers on long stems in loose clusters, followed by flat, oval, winged fruit (or samaras) that are less than 1 cm in length. These fall quickly, usually before the leaves are fully developed and are enjoyed particularly by grouse and squirrels.
Another elm found in our area is the Slippery Elm, so named because of its fragrant, ‘slippery’ inner bark. Found in southern Ontario and southern Quebec it does not attain the size of nor does it appear as graceful as its cousin, and may be found along streams and low slopes, either growing singly or in small clumps.
The third elm again found in southern Ontario and southwestern Quebec is the Rock Elm, with a mature one being somewhere in between the previous two in size. Usually with a trunk undivided almost to the crown, it can be distinguished by the corky ridges which appear like wings on its twigs and small branches. Growing on a variety of sites it nevertheless seems to prefer limestone ridges where there is less competition from other species.
Elm - a favourite urban tree both for its beauty and the shade. The Elm Streets found in many towns and cities may no longer have many elms as their names would indicate. Perhaps, just perhaps, the trees will develop an immunity to the disease that has wreaked its havoc, and some year in the future they will again spread their grace and beauty.