Ed. —Archived from the Sunday, Nov. 17, print edition.
VIRGINIA BEACH — You may know the tree of heaven if you’ve read A Tree Grows in Brooklyn. Despite its lovely name and its role in an American classic, the tree of heaven is one of the most noxious pests in Virginia.
I recently asked Virginia Beach Horticulture Extension Agent Ashton Holliday-Goulart to list the most harmful invasive plants in Virginia Beach, and tree of heaven was right up there near the top. It had company, too: mimosa, oriental bittersweet and Chinese privet.
The problem of aggressive, invasive plants has received a lot of attention in the recent past. This year, Virginia’s master gardeners’ continuing education programs and other projects have focused on identifying them and preventing their spread.
So what exactly makes a species invasive? And how does that differ from other non-native but more innocuous garden plants?
Holliday-Goulart quotes biologist Daniel Simberloff, who, in his book Invasive Species: What Everyone Needs to Know, defined invasives so: “Non-native organisms that cause harm to the environment, economy or human health.”
These invasives displace native plants and, because they usually provide no food for wildlife and can even be poisonous, they disrupt the food chain and potentially destroy an entire ecosystem.
Invasives differ from the pretty little annuals that don’t grow aggressively and, therefore, generally don’t replace native plants. It’s hard to pinpoint the worst invasives because Hampton Roads has so many, and some, such as phragmites, grow in wetlands or open spaces.
However, Holliday-Goulart considers some common suburban and urban plants as being among the area’s worst invaders. They include:
• The tree of heaven, or ailanthus altissima, is a rapidly growing tree that’s native to China. It’s sometimes referred to colloquially as “the paradise tree,” and it has compound leaves and rough bark.
The tree has some romantic connotations because, like the family featured in A Tree Grows in Brooklyn, it’s tough enough to thrive even in tough environments. Because it can tolerate pollution, it was once planted widely in cities, and it can be confused with the black walnut or the native sumac.
Tree of heaven grows rapidly, displaces other plants and, because its tough roots spread so quickly, can damage pipes. It can be toxic to nearby plants, and its twigs and the male flowers emit a foul odor.
As an adult, I began to fall out of love with mimosa when I saw how prolifically it was growing in the Jefferson National Forest. Then, I began to notice that General Booth Boulevard was lined with what seemed like hundreds of mimosa trees, and I realized what an aggressive nuisance it is. It spreads quickly through seeds and displaces native plants.
• Oriental bittersweet, or celastrus orbiculata, is described by Virginia Cooperative Extension as “a climbing, woody vine that can suffocate trees and spreads by seeds and sprouting of roots.” It was introduced to this country as an ornamental, and, with its pretty orange berries, it resembles native bittersweet.
It has smaller leaves, however, and the berries appear up and down the stem, while American bittersweet’s berries are at the end of the stem.
• Chinese privet, or ligustrum, is native to China but was introduced as an ornamental and became naturalized. The small blue berries, which look something like blueberries, are poisonous to humans, and the plant grows aggressively, displaces native plants, and is a bane to many local homeowners.
Unfortunately, many invasive plants are still sold in nurseries, so shop carefully and make sure that you do a little research before you buy plants.
If you are already cursed with them in your yard, it’s important to get rid of them, and you may be in for a lot of chopping, pulling and perhaps some herbicide application.
Virginia Cooperative Extension and the Virginia Department of Forestry also provide information on how to identify and eradicate them online at their websites.
The author is a contributor to The Independent News. Her journalism has also appeared in The Virginian-Pilot.
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