It’s spring! But – what’s green?

Dr. Bob Collier
Nature notes

If you’re reading this column on Wednesday, April 5, then you’ve already enjoyed two weeks of official springtime. And it’s been nice – after three nights of hard freezes, we’ve been having warm days, cool nights, occasional rain showers. The redbuds have rebounded from the cold snap into their usual luscious spring glory, and the cedars and elms are making pollen (Achoo!).

Most of the trees, though, are still a little skeptical of it all; the buckeyes and wild cherries are barely starting to peek out with some leaves. The wily walnut trees know better. They’re waiting, as the seed packets say, until “all danger of frost has passed.” Nevertheless, as we drive around in our part of the world here in Knox County and nearby environs, we are seeing a lot of bright, spring-fresh new green leaves. But notice – uh-oh – they seem to be growing on only a couple of kinds of plants. Tall bright green trees, shorter bright green undergrowth bushes.

We may be having some problems here, Houston. Look at the edges of the woods along I-75 or Highway 33. Those early green trees? They’re out way ahead of the usual early trees such as the poplars and the maples, serious competition for sunlight and nutrients. They aren’t from around here, as we say in East Tennessee. Actually, they are from across the water, brought to us from China by none other than the U.S. Department of Agriculture back around 1965. The Bradford Pear.

To make matters worse, all that exuberant understory shrubbery that has been up and growing for weeks now, completely filling some areas under the trees and lining our highways, is another foreign invader, native to China, Japan, and Korea, brought to us compliments of the New York Botanical Garden in 1898 – the dreaded Amur bush honeysuckle.

Now we know that there are at least two sides to every story, staunch differences of opinion – normal human behavior. Just look at politics – and religion! It’s that way with Bradford Pears. Lady Bird Johnson called them “the perfect tree.” The Tennessee Department of Environment and Conservation, in its publication The Tennessee Conservationist, calls them “evil dressed in white.”

Perfect tree? Well, yes, in a number of ways. The people who love them point out that they grow very fast – a great feature for contractors, useful for quickly transforming a brand-new subdivision onto a tree-lined neighborhood. The trees are a uniform, lollipop shape, they bloom profusely early in the spring, and have lovely red-to-maroon foliage in the fall. And they are disease and insect resistant; not even Japanese beetles will eat them.

But the dark side to the perfect tree is as follows: The Bradford Pear’s rapid growth also makes it vulnerable to a short life, average 20 years or less, because it is so subject to wind damage – broken limbs, split trunks. The monotonous, uniform, stamped-from-a-pattern lollipop shape of the trees is disagreeable to a lot of folks, who prefer to see their accustomed variety in the shapes of their trees. The flowers of Bradford Pears are notoriously malodorous, a smell described by some as resembling that of rotting flesh. The fruits, eaten mostly by starlings, drop in yards and onto cars as they deteriorate, and smell unpleasant as well.

And yet, the worst part is this: When those seeds that are eaten by birds are dispersed far and wide, and germinate and grow, they revert back to their ancestral Callery Pear, growing in dense thickets and bearing fierce, strong thorns that can penetrate a tractor tire or work boot. They aggressively crowd out our native trees and shrubs – a classic alien invasive species!

Those widespread bush honeysuckles? Well, they don’t sprout thorns, probably the nicest thing a person could say about them. But like many of the other invasives, they come out earlier in the spring, go dormant later in the fall, are disease and insect resistant, and out-compete the native shrubs, ground covers and wildflowers, spreading and growing fast and aggressively.

Their bright red berries, a selling point for them as an ornamental planting early on, are attractive to many bird species, and get dispersed by them, far and wide, often for miles from the mother plant. They can grow in full sun and deep shade, in wet or dry locations, and are lining the roadsides all over the eastern United States except for arctic Maine and tropical Florida. They have been banned in Connecticut and Massachusetts (believed to attract deer and bring an increase in Lyme disease), labelled a “noxious weed” in Vermont, and are on Tennessee’s, and others’, invasive species list.

These two bad actors are the ones that stand out at this time of the year, but there are many others. Think Japanese honeysuckle, Chinese privet, mimosas, kudzu, and the tree-strangling Oriental bittersweet. Garden escapees become serious invasives, too: winterberry, English ivy, burning bush, nandina. So, what to do besides wringing our hands and grumbling? Mostly, I would say, read up, be informed, remove exotics from your corner of the earth, and above all– shop wisely for whatever you plant and grow. The Tennessee Native Plant Society and the Tennessee Exotic Pest Plant Council both have websites with lots of useful information.

In checking the web, I found nurseries that are still offering both Bradford Pears and bush honeysuckles for sale! Find a good, reputable plant nursery to do business with, and let them know that you’re aware of the problems with alien invasives and don’t want them on your place! Enjoy the native plants, try some you haven’t used before. Hooray for the redbuds, dogwoods, wild plums, serviceberries, sugar maples and black cherries, silverbells, witch-hazels and sourwoods!

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