Euonymus alata, also known as burning bush, is at least a clear-cut villain, unlike some of the other invasives. I recall spending a long June day collecting vegetation data in an an immense Euonymus thicket, a former estate in Wilton. I did not even observe a catbird, the most common thicket songbird in Connecticut! And beneath the dense bushes, the ONLY plants growing were Euonymus seedlings.
This species must have high-powered chemical defenses. The glossy leaves look almost artificial (and might as well be), no holes where caterpillars or leaf beetles have nibbled. Pickings are slim for foliage-gleaning parent songbirds. No “chain migration” for this species with a suite of nearly pre-adapted species waiting in the new world, to make use of the new immigrant – and keep it in check, as has happened with the cherries. Gray’s Manual of Botany (Fernald) shows only two native cousins in this genus, and neither has a range that overlaps southern New England or Long Island.
Euonymus alata, from Asia, is an effective invader of forests, because it grows well in shade, unlike bittersweet, multiflora rose, everlasting pea, and Phragmites. It spreads well by runners as well as seed. Unfortunately, it thrives especially in the mineral-rich, sub-acidic soil of traprock (basalt) ridges.
Euonymus has overrun much of Peck Mountain, in north Cheshire, because suburban yards on the flanks of the traprock ridge provide abundant seed sources. As recently as the mid 1980’s the ridge crest and its steep talus slopes were botanically diverse and special. At that time they were clear-cut CTDEEP Critical Habitats, per the CTECO website (sub-acidic forest,sub-acidic talus slope, and sub-acidic summit catgories.) Since then, these habitats have become near monocultures of burning bush. The Euonymus even thrives in shallow soil pockets on ledges! Some rare Staphylea trifolia (bladdernut) and marginal wood fern remains on the steep west slope of Peck Mountain, and I last year I noticed a single non-blooming columbine patch. The oak fern, dwarf saxifrage, and anemonella appear to be gone.
After that Wilton experience and a recent eye-opening hike on Peck Mountain, I knew we had to get rid of the burning bushes in our own yard. Emotionally, it was not so easy. This is a beautiful shrub, especially when crimson in the fall, and it makes a dense, tidy hedge. The wings or flanges on the stems also look interesting in winter. Our bushes had special meaning because they been given to us by relatives who were dear to us.
Control was very quick and simple, from a practical standpoint. We snipped them with a lopper, and painted the freshly cut stems with Brush-B-Gon (8% triclopyr). For those who simply cannot kill their prize burning bush, thoroughly shearing off the seeds each September, with hedge clippers, will at least prevent further spread by birds.
Connecticut nurseries are still battling the environmental regulators, to prevent an outright ban of Euonymus alata, because this is such a popular, lucrative species for the landscaping business, especially for commercial sites.
For illustrations and discussion of other invasive plants, see the accompanying facebook album “Invasives- A Devil’s Advocate Perspective” (Sigrun Gadwa)