April 22, 2018
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Note to nurseries: No more invasives

Contributed | BDN
Contributed | BDN
By Reeser Manley

Euonymus alatus, known to some as winged euonymus for the four corky wings that appear occasionally along the young stems, to others as burning bush because of the bright crimson color of autumn leaves, is a non-native invasive plant. In other words, it is a noxious weed.

According to the Center for Invasive Species and Ecosystem Health, “winged burning bush can invade a variety of disturbed habitats including forest edges, old fields and roadsides. Birds readily disperse the seeds, allowing for many long dispersal events. Once established, it can form dense thickets that displace native vegetation. Winged burning bush is native to northeastern Asia and was first introduced into North America in the 1860s for ornamental purposes. It currently continues to be sold and planted as an ornamental or roadside hedge.”

I studied the invasion of burning bush at a site in Boothbay, a tract of land managed as a natural area but where burning bush, Oriental bittersweet, Celastrus orbiculatus, and Norway maple, Acer platanoides, all non-native invasive species, were fighting it out for dominance over native plant species. The burning bush was winning.

My graduate student and I traced the steady advance of burning bush over the half-century since the parent shrub was planted at an old home site. Colonies of seed-producing plants, some more than 100 yards from the home site, covered the ground beneath tall trees and nothing grew in the dense shade cast by these shrubs except their own seedlings; all native shrubs and tree seedlings had been eliminated.

Maine nursery owners could take the lead in educating the gardening public about the threat of invasive species to natural areas, much like their counterparts in New Hampshire. In 2007, all varieties and cultivars of Euonymus alatus were added to a list of 18 invasive species prohibited from sale, transport, distribution, propagation or transplantation in New Hampshire.

Instead, many nurseries in Maine have chosen to disregard the facts and continue to sell burning bush, Japanese barberry, Norway maple and other invasives. They have chosen to profit from customer ignorance about the threat of invasive species to natural areas.

Informed gardeners who care about the future of Maine’s natural areas must lead the way. No more invasives! We must insist on noninvasive alternatives to burning bush and encourage our friends to do the same.

There are alternatives, both native and non-native. In the past I have recommended highbush blueberry, Vaccinium corymbosum, a native shrub with dark-red fall foliage, lovely flowers and delicious fruits, as an alternative to burning bush. A non-native shrub, the redvein enkianthus, Enkianthus campanulatus, is worthy of addition to the list.

The enkianthus in Marjorie’s garden, now in its 10th year, is flowering this week, clusters of creamy yellow bells with deep red veins hanging below the whorl of leaves at each branch tip. The flowers are slightly larger that those of high-bush blueberry but have the same drooping habit. The fruit is a dry seed capsule and the tiny seeds are not dispersed by birds into natural areas.

Now about 8 feet tall, we have pruned this naturally shrubby plant into a small multitrunk tree, highlighting its layered branches. It may eventually grow to 12 feet in height, the perfect small garden tree. Kept in shrubby form, redvein enkianthus makes a beautiful informal hedge.

In autumn the leaves on our plant turn to a mix of brilliant red and gold. Fall color is variable within the species with some plants turning all red — a better red than burning bush — or all yellow, but cultivars have been selected for red fall foliage, others for deep red flowers.

Redvein enkianthus is recommended as a replacement for burning bush by University of New Hampshire Cooperative Extension and by Massachusetts’ nurseries. Maine nurseries should do the same.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to rmanley@shead.org. Include name, address and telephone number.

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