I was pleased to see an update on the invasive potential of burning bush, Euonymus alatus, in the latest Regional Gardening Report, an online publication of the National Gardening Association. Reporter Susan Littlefield summed up the current situation, stating that “here in New England, we’ve been burned by the burning bush. Throughout our region, this shrub has jumped its cultivated bounds and earned a spot on states’ invasive species lists by spreading too readily into fields, open woods, and mature forests, as its seeds are disseminated widely by wildlife species in their droppings.”
That burning bush (also called winged euonymus) is invasive is not news. While at the university 10 years ago, I worked with a graduate student on an invasion of burning bush in the Boothbay area where we quickly recognized its potential to alter the understory vegetation. It had formed extensive colonies of reproductively mature plants in the understory of a white pine forest, eliminating all native shrub and tree seedlings. The only vegetation growing beneath the dense shade cast by these shrubs were burning bush seedlings.
The good news is that two New England states, Massachusetts and New Hampshire, have laws that prohibit the sale of Euonymus alatus, while Vermont is considering similar legislation this year. Meanwhile, many environmentally conscious nurseries throughout the region voluntarily have agreed to stop selling burning bush.
Late September and early October are a great time of year to remove burning bush plants from the garden and replace them with plants that offer outstanding fall color without posing a threat to natural areas. Littlefield offers three native alternatives to burning bush, two of which I also would recommend for Maine gardens.
With autumn leaves of dark red, plum and yellow, highbush blueberry (Vaccinium corymbosum) is every bit as striking in fall as burning bush. Unlike burning bush, strictly a one-season plant with inconspicuous flowers, highbush blueberry also has pendulous clusters of white flowers in spring and delicious summer fruits.
Red chokeberry (Aronia arbutifolia), a deciduous shrub native to the eastern United States, grows best in full sun and moist, well-drained soil. Fragrant white flowers in spring, red berries in summer and red fall foliage make this a three-season plant. The cultivar “Brilliantissima” is the best selection for red fall color.
My preference among the chokeberries is Aronia melanocarpa, the black chokeberry.
White flowers with pink anthers open midspring among shiny dark green leaves, followed by glossy black fruits that persist from late summer into winter. The dark fruits provide striking contrast to this shrub’s crimson fall foliage.
Littlefield suggests using wild raisin (Viburnum nudum cassinoides) to replace burning bush, stating that it is less susceptible to the viburnum leaf beetle, another non-native invasive species that has destroyed countless arrowwood viburnums and cranberry viburnums in Maine.
Unfortunately, I have seen severe leaf beetle damage to wild raisin in the Ellsworth area (including one in our garden) and cannot recommend planting it.
I would add a non-native shrub, the redvein enkianthus (Enkianthus campanulatus), to the list of burning bush alternatives. The enkianthus in Marjorie’s garden, now in its 10th year, bears early-June pendulous clusters of creamy yellow bells with deep red veins. A cluster of blossoms, slightly larger than those of highbush blueberry but with the same drooping habit, subtends the whorl of leaves at each branch tip.
The fruit of enkianthus is a dry seed capsule with tiny seeds that are not dispersed into natural areas. There is no evidence that this non-native ornamental shrub is invasive.
Now about eight feet tall, we have pruned this naturally shrubby plant into a small multi-trunk tree, highlighting a layered branching habit similar to that seen in rhododendrons. It may eventually grow to 12 feet in height, the perfect small garden tree. Kept in shrubby form, redvein enkianthus also makes a beautiful informal hedge.
In autumn the leaves on our enkianthus 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. 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.
Indeed, Maine nurseries should get on the bandwagon and stop selling burning bush and other invasive plant species. There are too many suitable alternatives, both native and non-native, that do not threaten the future of Maine’s natural areas.
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