Have you ever done something with very good intentions only to have it go horribly wrong? Well, it is no different with gardeners and horticulturalists. We all make mistakes and some of the biggest horticultural mistakes in our country have been made by well intentioned and often highly accomplished professionals. Throughout our history, shrubs, plants, and trees have been introduced into North America in the hope that they would provide value to the landscape. Sometimes this has led to unforeseen disastrous results.
Take for example a tree that has been in the news for the past ten years or so – the Bradford or Callery pear. This tree was imported from East Asia in the early 1960’s by the United Stares Department of Agriculture as the perfect landscape tree. The New York Times touted it by proclaiming “Few trees possess every desired attribute, but the Bradford ornamental pear comes unusually close to the ideal.” It was planted in parks, shopping center parking lots, and along busy highways. Since it blooms early in the spring and has brilliant fall color that lasts for a long time, what is not to like?
Unfortunately, the tree proved to be less than perfect. It sends out suckers that need to be trimmed. The branches are weak due to its growth habit and break in storms. The blossoms do not attract pollinators, but only flies. The flowers smell offensive and although Bradford pear was supposed to be sterile, it spreads by seeds and roots. From the perfect tree, it went to being labeled as the neighborhood enemy number one. Thirty year later the New York Times wrote that the darling tree of the past has “morphed into an unstoppable villain.” How the mighty have fallen. South Carolian was one of the first states to ban its sale and now most states recognize this tree as invasive.
Another accidental invasive is Elaeagnus or Autumn Olive. There are over 90 species of Elaeagnus and most originate in the temperate and subtropical areas of Asia. It is widely used in Europe as an ornamental and is thought to have been introduced into this country in the late nineteenth century. Like the Bradford pear, Elaeagnus was imported to this country for purpose. The plant is salt tolerant, will grow in poor soils, and can be used to control erosion. Once in this country, Elaeagnus more than flourished. The variety that grows here has become highly invasive spreading by roots and seeds and pushing out other plant species. It can take over an entire area growing into a thick and tall hedge. The fall flowers have a wonderful scent and birds spread the plant by the fruits. In Europe, the fruits never ripen so it does not become invasive. South Carolina banned the sale of Elaeagnus along with the Bradford pear on October 1, 2024.
The last accidental invasive to be discussed is the Chinese tallow tree, a native of east Asia. When it is a sapling, this is an adorable little tree with bright green leaves that look a little like aspen leaves… I hated pulling them out when I was part of a tallow tree removal team. When they are full grown, they are large and they aggressively take over wherever they grow and crowd out native flora. Tallow trees were brought to South Carolina, Georgia, and Florida in 1973 by one man who thought that the oil producing seeds would be useful. The seeds are useful and the oil is used in paint drying compounds. The ecological damage though is not worth it. I have seen tallow trees in the ACE basin dominating the landscape. Best to “catch” them when they are small.
What should you do if you have any of these accidental invasives? You are not required by law to remove them, but you can no longer purchase them. In the case of Elaeagnus, it makes a dense hedge if you are trying to hide or block something. I have some between my house and my neighbor’s and we just keep it under control and watch for errant seedings. Tallow trees should be removed if possible. Many communities have groups that check for tallow trees and eradicate them while they are still small. In the case of Bradford pears and the even more invasive sibling known as Callery pear, Clemson has a tree bounty system. If you give evidence that you have dug out or cut down an offending pear tree, they will give you a free native tree to replace it. Check out their website for information at https://www.clemson.edu/extension/bradford-pear/
It does seem sad that these species were introduced for specific purposes and that no harm was intended. No one could foresee what the consequences would be. I suppose the lesson learned is that while assisting Mother Nature can have its rewards, it can also have its penalties.
