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The war of the trees

Bill Meredith

Loveliest of trees, the Cherry now
Is hung with bloom along the bough,
And stands along the woodland ride,
Wearing white for Eastertide.
Now, of my threescore years and ten,
Twenty will not come again,
And take from seventy springs a score,
It only leaves me fifty more.
And since to look at things in bloom
Fifty springs are little room,
About the woodlands I will go
To see the cherry hung with snow.
~A. E. Housman, ca. 1880

(5/2017) One day in 1989 my wife and I looked at each other and realized that our house seemed empty. Our children had moved away, and grandchildren had begun to appear; they visited sometimes, but most of the time the house had a vacant feeling. So we built a new house, designed so we could live on one floor as age accumulated. There was an upper story, but it was for the occasional visitors and for stuffing full of things that should have been thrown away.

My favorite aunt had visited us every summer since we came to Emmitsburg in 1957, and she came to see the new house in 1990. She approved of it on the inside, but she could not help noticing that the outside looked barren. We had built it in our former garden, and grass was beginning to grow around it, but there was not a shrub or tree in sight. So she gave us a check and told us to buy a tree. She didn’t specify what kind, so after some searching we selected a weeping cherry; and since her name was "Icky," it became the Icky Tree.* She visited us two more times before she died, at the age of 92, so she never got to see what a truly beautiful gift the tree was to become, nor to share the pleasure it brought when our grandchildren came every spring to hunt Easter Eggs under it and have their pictures taken.

It is one of my regrets that I had not yet discovered Housman’s poem while Icky was still living. She liked poetry; she wrote a bit herself, and she read to me when I was a child. She would have smiled ruefully at the irony of the situation. The cherry sapling was five feet high and barely an inch thick when we planted it, and I had already used up 80% of my three-score years and ten. But it grew steadily; it is now about 15 inches thick at ground level, and stands some 30 feet tall. It has bloomed around Easter every year, and once again this year it was the loveliest of trees, as Housman foretold… but it is dying. Last summer two large branches died, and when the bloom came out this spring about half of the remaining branches were bare. I don’t know how many scores of years a cherry tree is allotted, and of course no one knows the future; but the odds now are at least 50:50 that I will live longer than the tree does.

If you look at the cherry tree now, the source of its trouble is obvious; it is a caused by a Bradford pear tree that was planted the same year as the cherry, and is now some 15 feet taller. When we went to buy the cherry tree, there was a sale at the nursery, and my wife brought home eight or ten other trees, including four Bradford pears. I planted one of them about 20 feet from the cherry. It flourished, and as it matured, it began to release a chemical substance into the air that is toxic to the cherry tree. Over the past few years the amount of this substance increased; the branches of the cherry on the side toward the Bradford pear stopped growing, and last year they began to die. So I have to take responsibility. I should have known better.

Long before I ever took a course in botany, I knew that different kinds of plants are at war with each other. The basic idea is quite old; around 300 B. C., the Greek scholar, Theophrastus, wrote that walnut trees caused "soil sickness," damaging the soil to prevent other trees from growing near them. My father probably never heard of Theophrastus, but he knew about walnut trees, and he showed me that other kinds of trees did not germinate under the walnuts on our farm. He said this was because the walnut roots released something into the soil which killed other trees. He may have learned that as a boy when he helped his grandfather cut timber for his sawmill; and he probably read about it in his farm magazines in the 1930s. Biochemists had discovered the chemical substance produced by walnuts around 1850, and by the time I was born similar chemicals had been found in many other plants.

These chemicals belong to a class of substances called Allelopaths, and they are quite common in nature. In a forest, many species of trees produce them to gain a competitive edge in the "struggle for survival." This has been going on for millions of years, so the native trees also developed some degree of resistance to them… in other words, a "balance of nature" occurs. However, when new species of plants are introduced into an ecosystem, the native species may not be resistant to the new allelopaths, and the introduced species then becomes invasive, crowding out the natives. Common examples of this are Mulberry, Tree of Heaven, Japanese Honeysuckle, and some oriental chestnuts; each produces its own kind of allelopath. And this is not limited to trees; the Allelopath War goes on among many herbaceous weeds as well. The best example locally is garlic mustard; it was unknown around here before the 1980s, but it now carpets most of the woodlands that have grown up on abandoned farmlands. It has crowded out many of our native wildflowers.

On reflection, the "War of the Trees" may not be the best metaphor to use in discussing allelopaths. I think it would be better to define "War" as human conflict because it involves thought and decision-making. There are many kinds of war… wars of conquest, religious wars, civil wars, just wars, colonial wars, wars caused by greed or immorality among leaders, to name a few. Ethical concepts such as good or evil and right or wrong are involved.

The interactions between plants are different; they do not involve logical planning or personal feelings, and there is no moral dimension to them. In undisturbed ecosystems, over a long time they result in a balance between competing populations. This balance is inevitably imperfect; all species eventually become extinct, and mass extinctions have occurred at least five times in the earth’s history. But these mass extinctions have been the result of external forces, such as meteors or volcanoes; between them, life has recovered and stabilized. In the main, interactions between plants and animals have resulted in food chains, which apportion the energy from sunlight to many different species of both plants and animals. In this process, individuals get killed and eaten, but populations maintain a relative stability. In the perspective of human values, this seems harsh; but it is how life has persisted for the past five billion years.

* The story of Icky’s unusual name was told in an article called "Of Fools and Rain and Easter Under the Icky Tree," in The Emmitsburg Dispatch, May 2001. You can read it on-line at

Read other articles by Bill Meredith