Burning Bush or Winged Euonymus

(Celastraceae - Staff-Tree Family)

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• Form
  • large-sized foliage shrub
  • specie form very slowly maturing at 15' tall by 15' wide
  • cultivars are smaller (10' by 10', or less, making them medium-sized shrubs), and often are kept to an even smaller size by shearing, irrespective of their specific genetic potential for size
  • upright vased growth habit in youth, becoming spreading rounded and horizontally layered with age (if rarely or never pruned)
  • slow growth rate

• Culture
  • full sun to full shade
  • prefers moist, well-drained, slightly acidic soils in full sun, but is very adaptable to poor soils, compacted soils, various soil pHs, heat, drought, periodic shearing, and pollution (and is therefore very urban tolerant), and is also quite adaptable to partial to full shade (where growth is less vigorous and fall color is a mixture of pink-red and faded yellow)
  • propagated primarily by rooted stem cuttings, but also by seeds
  • Staff-Tree Family, with several significant problems that may affect this species:
    • Coral spot Nectria canker is a fungal disease that may infect the bark, cambium, and sapwood of the stems, branches, and/or trunk; this opportunisitic pathogen is especially infectuous after late Summmer pruning, severe Winter freezes, or severe drought, transplant shock, or root pruning, and causes significant dieback of the shrub in Spring, or eventual death of the shrub
    • Winged Euonymus scale is a significant pest problem when it occurs, sucking the sap from the stems and branches and leading to a signficant decline or slow death of the shrub; this pest is brown- to gray-colored and is a different species of scale as compared to the common white-colored "Euonymus scale" (which typically does not infect Winged Euonymus), but the result is the same
    • Hardwood mulch-induced nitrogen deficiency is a common physiological problem that can be remedied by a yearly fertilization regimen, or by switching to one of several slower-degrading mulches (for example: pine, cypress, or cedar) other than hardwood mulch (which decomposes relatively quickly by microbial action; these bacteria and fungi may rapidly deplete essential nutrients [especially nitrogen] from the soil beneath, thus depriving the plant's roots from absorbing the same nutrients)
    • placement of this shrub in alkaline soils may result in mild leaf chlorosis, which once again can be remedied by a yearly fertilization program
    • the last three of these problems (along with prolonged Summer drought) may manifest themselves in their early stages by the common symptoms of leaf chlorosis and premature fall color; which one (or more) of the three possible causes is the culprit requires a combination of close scrutiny (looking at every branch, are scales present in the usually green portions of the stems?) and common sense (is hardwood mulch present? are the soils of the area generally alkaline in their pH?)
  • abundantly available in ball and burlap or container forms
  • plants that are too large and oversheared will respond well to rejuvenation pruning in early Spring (severe pruning from 0.5' to 2' above the ground), having relatively few stems the first year, but branching out nicely in the second and subsequent years

• Foliage
  • medium to dark green, 1" to 3" long, with a short petiole
  • opposite to subopposite, elliptical to obovate, with finely serrated margins
  • fall color is a brilliant flaming red in sunny sites or a faded pink-red in shady sites, yielding a consistent and often spectacular Autumn display

• Flowers
  • yellow-green miniature inflorescences in late May and early June, usually inconspicuous and hidden among the expanded foliage

• Fruits
  • many individual plants and/or cultivars have sparse fruits, if present at all
  • for those shrubs with a moderate to heavy fruit load, fruits are relatively small and often ornamentally inconspicuous, being hidden amongst the foliage
  • small green Summer fruits mature to a beige-red capsule, which dehisces (splits open) to show a few orange fruits in September just before fall coloration, often concealed by the red Autumn foliage

• Twigs
  • for the species form, very narrow dark green strips occur along the axis of the thick stem, surrounded by very prominent tan to brown corky wings
  • the common cultivar 'Compacta', however, has relatively thin stems that are primarily green, and the corkiness is replaced by thin tan strips interrupting the subtle green color

• Trunk
  • brown and slightly fissured, usually multitrunked and branching very low to the ground
  • with advanced maturity, some shrubs (especially the species form) can be limbed up into multitrunked tree form, or truly "specimen" shrub form

• ID Summary
  • opposite, elliptical, serrated leaves form a shaded canopy in the densely-stemmed shrub, being dark green in Summer and flaming red in Autumn
  • the species form and select cultivars (both being rarely available) have prominently corky stems with a hint of green in the non-corky regions, while the cultivar 'Compacta' (the overwhelming and often singular choice) has the situation reversed, with subtlely green stems being interrupted by longitudinal hints of corkiness
  • creamy-green flowers and beige-orange fruits (prominently displayed in some other members of the genus) are subdued, sparse, and rarely noticed for this species
  • growth habit is vased in youth, and, if rarely or never sheared, becomes rounded and horizontally layered in its branching with maturity

• Function
  • formal or informal hedge, group or mass planting, non-thorny barrier, deciduous screen, specimen, border, entranceway, foundation, or at water's edge (outstanding red color reflection in Autumn, but not wet site tolerant)

• Texture
  • medium texture in foliage, and medium (non-corky stemmed) to bold (corky stemmed) texture when bare
  • thick density in foliage and when bare

• Assets
  • brilliant flaming-red fall color
  • takes well to pruning and shearing
  • urban stress tolerant
  • vased shape in youth and layered horizontal branching at maturity (if unpruned)
  • ornamental winged stems (on the species form and some little-known cultivars)

• Liabilities
  • whether pruned or unpruned, it often slowly grows beyond its intended boundaries or presumed mature height
  • several biotic and abiotic stresses (disease, pest, and nutritional deficiency problems) can be significant for this species, compounded by its being overutilized in the landscape
  • may slowly sucker from its base or roots with age, forming tight colonies at maturity if these are not regularly nipped off
  • some plants may become leggy with age

• Habitat
  • zones 4 to 8
  • native to Northeastern Asia and Central China

• Alternates
  • shrubs with good fall color (Aronia arbutifolia 'Brilliantissima', Fothergilla gardenii, Hamamelis x intermedia, Viburnum rufidulum, Viburnum setigerum, etc.)
  • shrubs that may serve as formal or informal hedges (Ligustrum obtusifolium, Ribes alpinum, Taxus x media, Thuja occidentalis 'Smaragd', Viburnum dentatum, Viburnum lantana, etc.)

• Variants
  • virtually all cultivars of Burning Bush are more compact than the species form, but they differ primarily in how compact they are, how corky or non-corky the stems are, cold hardiness, upright versus rounded shape, and whether they branch to the ground versus become leggy with age; the following is an expanded list of modern cultivars:
    • Euonymus alatus 'Bailey Strain' - similar in all aspects of appearance to 'Compacta', but hardy to zone 4; rare availability
    • Euonymus alatus 'Compacta' - a "compact" form maturing slowly at 8' tall by 8' wide, with virtually no corky wings on its first-year, relatively thin, but more dense green stems, but only hardy to zone 5; the most popular cultivar by far and abundantly available; sometimes alternatively spelled Euonymus alata 'Compactus'
    • Euonymus alatus 'Nordine Strain' - heavily cork-barked, branching to the ground, to 10' tall by 10' wide, hardy to zone 4; low availability
    • Euonymus alatus 'Phellomanus' - heavily cork-barked, to 10' tall by 10' wide, hardy to zone 4; rare availability
    • Euonymus alatus 'Rudy Haag' - similar in appearance but much smaller than 'Compacta', slowly growing to 5' tall by 5' wide, hardy to zone 4; rare availability
    • Euonymus alatus 'Synnestvedt' - branching to the ground, to 10' tall by 10' wide, hardy to zone 4; rare availability

• Translation
  • Euonymus translates as "good name" (used ironically, since this genus once had a bad reputation for poisoning cattle).
  • alatus (sometimes alternatively spelled alata) translates as "winged," referring to the corky stems of the species form.

• Purpose
  • Burning Bush is a shrub noted for its excellent flame-red Autumn coloration and its ability to be easily sheared into hedge form.

• Summary
  • Euonymus alatus is a tough but overutilized landscape shrub primarily found as the cultivar 'Compacta' in mass plantings or as a formal hedge, widely known for its brilliant red autumnal display, and lesser known for the bold-textured corky stems that have Winter appeal on the underutilized species form.