Authors: Tunyalee Martin, Global Invasive Species Team, The Nature Conservancy
- Euonymus alatus is a deciduous shrub, up to 20 ft. (6.1 m) in height, which invades forests throughout the eastern United States. Two to four corky ridges often form along the length of young stems, though they may not appear in shaded areas or closed canopies.
- The opposite, dark green leaves are < 2 in. (5 cm) long, smooth, rounded and taper at the tips. The leaves turn a bright crimson to purplish color in the fall.
- The flowers are inconspicuous, are greenish yellow and have four petals. Flowers develop from late April to June and lay flat against the leaves.
- The fruit which appears from September to October are reddish capsules that split to reveal orange fleshy seeds.
- Ecological Threat
- Euonymus alatus can invade not only a variety of disturbed habitats including forest edges, old fields, and roadsides but also in undisturbed forests. Birds and other wildlife eat and disperse the fruit. Once established, it can form dense thickets, displacing native vegetation. It is native to northeastern Asia and was first introduced into North America in the 1860s for ornamental purposes. This plant is still sold and planted as an ornamental.
The name "winged" derives from the prominent corky wings along the stem, while the generic English name "spindle" refers to the use of the very hard wood [of European Spindle E. europaeus] being the traditional wood used for making spindles for spinning wool. The name "burning bush" is from the fall color of the leaves. Euonymus, roughly translated, comes from the Greek meaning "good name" or "of good repute". The species name alatus means "winged", as above. Synonyms include Celastrus alata Thunb. (basionym), Celastrus striata Thunb., and Euonymus striata (Thunb.) Loes.
Euonymus alatus (Thunb.) Siebold (Celastraceae, the staff-tree family) is a deciduous shrub. It is slow growing but can reach 1-4 metres (rarely to 6 meters) in height and width. The bark is gray-brown and the stems have prominent, corky wings running along both sides. In some plants, these wings can be greatly reduced to mere ridges. The leaf-buds are brownish-green, and strongly divergent. The leaves are opposite, elliptic, and measure 3-10 cm long and 1-4 cm wide with fine, sharp serrations on the margin. In autumn the dark green leaves turn a brilliant purplish red to scarlet color before dropping to the ground. The flowers are small, yellowish green in color and inconspicuous; flowering is from April to July. The smooth, four-lobed red-brown fruit are 1-1.3 cm long and are ripe from July to November. Each fruit contains up to four red to orange seeds, though often only one to three develop.
This new invader is becoming increasingly common in Connecticut, Virginia, Pennsylvania, and Illinois. It has been observed making dense thickets in Pennsylvania. These thickets can shade out native herbs and crowd out native shrubs. Euonymus alatus also has the following characteristics:
- Euonymus alatus is adaptable to various environmental conditions; it grows well in different soil types and pH levels, has no serious pest problems in North America, and most importantly of all is tolerant of full shade.
- Spectacular fall foliage makes it a popular landscape ornamental plant. Wide usage of this plant increases the probability that more will escape from cultivation.
Seed production is abundant. Birds relish eating the fruit, and seeds passing through their digestive tract are viable. Seeds dispersed this way germinate easily and spread the infestation to other areas.
Euonymus alatus is native to northeastern Asia from Japan through Korea to central China.
As a non-native, it is found in the USA from New England to northern Florida and the Gulf Coast. It is hardy to USDA Zone 4. Populations have been found in mature white oak upland forest and open, second growth lowland forest. Other populations have been found dominating pastures, the understory of shady hillsides, small ravines in valley floor forests, and glacial drift hill prairies.
Euonymus alatus was introduced into the USA from northeastern Asia around 1860 for use as an ornamental shrub. The bright red fall foliage of E. alatus makes this shrub a popular ornamental planting, and it is commonly planted along interstate highways, as hedges, and in foundation plantings. While it behaves well in urban areas, E. alatus planted near woodlands, mature second-growth forests, and pastures can be problematic. It has been observed escaping from cultivation in the northeast and midwest, notably in Connecticut, Virginia , Pennsylvania , and Illinois. Euonymus alatus is a threat to woodland areas, fields, and coastal scrubland because it outcompetes native species.
Control of this plant is difficult because it produces a tremendous amount of seed. Suggested control methods include:
- Seedlings up to 60 cm (2 feet) tall can be easily hand-pulled, especially when the soil is moist. Larger plants and their root systems can be dug out with a spading fork or pulled with a weed wrench.
- Larger shrub can be cut. The stump must be ground out or the re-growth clipped. The cut stump can also be painted with glyphosate immediately after cutting, following the label directions. Where populations are so large that cutting is impractical, herbicide (glyphosate) may be applied as a foliar spray. This is most effective during the early summer months.
- An extremely labor intensive method to prevent spread is to trim off all the flowers.
- Plant native or non-invasive alternatives such as spicebush (Lindera benzoin), Strawberry bush (Euonymus americanus), maple-leaf viburnum (Viburnum acerifolium), wild hydrangea (Hydrangea arborescens), highbush blueberry (Vaccinium corymbosum), native red chokeberry (especially the cultivar Aronia arbutifolia 'Brilliantissima') or the non-invasive exotic Korean spice viburnum (Viburnum carlesii). Ask your local native plant society for further alternatives.
Unsuccessful control measures include mowing small plants and then spraying one month later with triclopyr salt (360 g ae/l), triclopyr ester (480 g ae/l), or triclopyr ester (120 g ae/l) plus 2,4-D (240 g ae/l) applied at 1% to runoff.
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Images from Bugwood.org