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Euonymus alatus (Thunb.) Siebold
(burning bush, winged euonymus, winged wahoo, winged spindle-tree, Japanese spindle-tree)


Summary: known invaders sighted in new areas
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 [11], Virginia [6, 9, 10], Pennsylvania [5], and Illinois [1, 3, 8]. E. alatus is a threat to woodland areas, fields, and coastal scrubland because it outcompetes native species.

Description:
(Click on thumbnail images for a closer view)

Fall fruit & leaves

Fall foliage

Escaping seedlings

Unwinged stems

Winged stems

Euonymus alatus (Thunb.) Siebold (Celastraceae--the staff-tree family) is a deciduous shrub. E. alatus is slow growing but can reach 4.6-6.1 meters in height (and width). The bark is gray-brown and the stems have prominent, corky wings running along both sides. In some cultivars, 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 2.5-7.6 cm long and 1.3-3.2 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. In Pennsylvania the flowers bloom in late April to late June. The flowers are small, yellowish green in color and inconspicuous. The smooth, purplish fruit are 1.3 cm long and are present in September through October. Each fruit contains approximately four red to orange seeds.

Scientific and Common Names:
The common name, "winged euonymus", is derived from the corky wings along the stem. 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, is in reference to the prominent corky wings on the stems of the shrub. Synonyms for E. alatus include "Celastrus alata Thunb.", "Celastrus striata Thunb.", and "Euonymus striata (Thunb.) Loes.".

Impacts:
This new invader is becoming increasingly common in Connecticut, Virginia, Pennsylvania, and Illinois. It has been observed making dense thickets in Pennsylvania [5]. These thickets can shade out native herbs and crowd out native shrubs. Euonymus alatus also has the following characteristics:
1)E. 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.
2)Spectacular fall foliage makes it a popular landscape ornamental. Wide usage of this plant increases the probability that more will escape from cultivation.

Native Range:
Euonymus alatus is native to northeastern Asia to central China.

Range As An Invader:
Euonymus alatus 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.

Reproduction and methods of Dispersal:
Seed production is prodigeous. 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.

Control:
Control of this plant is difficult because it produces a tremendous amount of seed. Suggested control methods include:
1)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.
2)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.
3)An extremely labor intensive method to prevent spread is to trim off all the flowers.
4)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 (3 lb ae/gallon), triclopyr ester (4 lb ae/gallon), or triclopyr ester (1 lb ae/gallon) plus 2,4-D (2 lb ae/gallon) applied at 1% to runoff.

References:
1)Behnke, G. and J.E. Ebinger. 1989, Woody invasion of glacial drift hill prairies in east-central Illinois. Transactions of the Illinois Academy of Science, vol. 82(1&2):1-4.
2)Dreyer, G.D. 1988, Efficacy of triclopyr in rootkilling oriental bittersweet (Celastrus orbiculatus Thunb.) and certain other woody weeds. Proceedings of the Northeastern Weed Science Society pp. 120-121.
3)Ebinger, J.E. 1983, Exotic Shrubs A Potential Problem in Natural Area Management in Illinois. Natural Areas Journal, vol.3, no. 1:3-6.
4)Randall, J.M. and J. Marinelli (eds.) 1996, Brooklyn Botanic Garden Invasive Plants: Weeds of the Global Garden, p.55.
5)Rhoads, A. Director, 2000, Pennsylvania Flora Project at the Morris Arboretum. Personal communication.
6)http://www.vnps.org/invasive/complete_list.html
7)http://spirit.lib.uconn.edu/CANR/plsci/mbrand/e/e.html
8)http://webriver.com/tn-eppc/symposium/harty.htm (A now-dead link)
9)http://www.vnps.org/invasive/invfseual.htm
10)http://www.geocities.com/RainForest/Vines/2996/invasives.htm
11)http://darwin.eeb.uconn.edu/ccb/publications/publication-1.html
12)http://www.orst.edu/dept/ldplants/

--Tunyalee Martin/Wildland Invasive Species Team; March 2000



Updated October 2006
©The Nature Conservancy, 2000