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Eastern Redbud (Cercis Canadensis) was selected as the Society of Municipal Arborists (SMA) Urban Tree of the Year by the SMA. Cercis Canadensis, is also commonly called Redbud or Judas Tree. This last name, according to legend, is the result of the biblical Judas Iscariot hanging himself from a branch of the European species Cercis siliquastrum.

The 2010 Urban Tree of the Year: Eastern Redbud

By Len Phillips


 


 Eastern Redbud (Cercis Canadensis) was selected as the Society of Municipal Arborists (SMA) Urban Tree of the Year by the SMA. Cercis Canadensis, is also commonly called Redbud or Judas Tree. This last name, according to legend, is the result of the biblical Judas Iscariot hanging himself from a branch of the European species Cercis siliquastrum.


Eastern Redbud is a moderate to rapid grower when young, often maturing 15 feet tall by 15 feet wide, but it can become 35 feet high on moist sites. The tree’s rapid growth rate slows to a medium growth rate after 10 years of age. Eastern Redbuds are native to Eastern and Midwestern United States. Oklahoma calls Eastern Redbud its state tree.


 


Description


The flowers of the species open as small clusters of dark-brown buds that swell to purple-lavender buds in early spring. They slowly open to magenta or pink-lavender flowers, prominently displayed in April before the foliage emerges. The blooms persist for two to three weeks. The flowers can be found on the trunk or branches, but most are found on two-year-old twigs.


In the spring, the leaves are bronze to medium green, slowly turning to dark green, and about 4 inches long by 4 inches wide in summer. The leaves are alternate, broadly ovate with distinctly cordate bases. The heart-shaped leaves have prominent palmate veination.


Eastern Redbud twigs have a zigzag pattern and show cream-colored lenticels. The color is dark brown with subtle shades of purple or red in the stem color. The vegetative lateral buds are small and purple-brown, while floral buds are slightly more plump and in clusters along stems, branches and trunks.


The trunk is either single-trunked and low-branching, or multitrunked and shrub-form. The exterior bark is brown-gray with thin exfoliating strips or thin fissured plates in youth that become crisscrossed and raised with age. The cinnamon-orange interior bark reveals itself with age. The trunks become twisted, leaning and decayed with age.


The small black seeds are within flat light-green “pea-shaped” pods that change to brown when the seeds are ripe. They are located in clusters on the twigs. The dried pods may persist for a year or more and provide some winter interest. Heavy seed crops do not occur every year.


 


Habitat


 When grown in an open area, Eastern Redbud develops an upright vase form in youth and with age, becomes spreading and rounded to develop an irregular shape, and often develops a lean. When grown at the edge of forests and woodlands, it is often found with an irregular shape because it stretches toward the limited sunlight.


Eastern Redbud grows well in full sun in the northern part of its range, but will benefit from some shade in the southern zones — particularly in the Midwest where summers are hot. Best growth occurs in a light, rich, moist soil but this tree adapts well to a variety of soils including sandy and alkaline. The trees look better when they receive some irrigation during summer dry spells. In very wet sites, it is prone to verticillium wilt.


The species is propagated by seeds, while the cultivars are usually budded onto seedling rootstock or by summer cuttings under mist. Ripe seed can be planted directly but stratification is necessary if seed has been stored. Trees are sold as single or multi-stemmed trees, B&B or in containers. Young trees are easiest to transplant and survive best when planted in the spring or fall. Containerized trees can be planted anytime.


 


Uses


The yellow fall color and tolerance to partial shade make this a suitable, attractive tree for understory or specimen planting. It is best if this tree is not used as a street tree due to its low disease resistance and short life span. It is nice in commercial and residential landscapes. The tree also does well in a shrub border for a spring and fall color display. It is often used as a foundation plant; a specimen; at an entranceway; as a group planting; along a woodland edge; in a naturalization planting; or as a spring accent tree. The seeds provide food for some birds. Eastern Redbud is not a commercial timber species.


Eastern Redbud works well in combination with Serviceberry (Amelanchier), Flowering Dogwood (Cornus florida), Carolina Silverbell (Halesia Carolina), Crabapple (Malus), Chinese Dogwood (Cornus kousa), and Japanese Tree Lilac (Syringa reticulate). It is often the first of a floral sequence of ornamental trees.


From a design standpoint, Eastern Redbud is medium to coarse in texture and has thick density in leaf. The tree is average in density when bare, such as during the winter months.


 


Cultivars


Several cultivars of Eastern Redbud are available:

‘Flame’ — more erect branching, flowers double, blooms later, sterile,
‘Forest Pansy’ — purple-red leaves in spring, fades to green in the summer,
‘Pink Charm’ — pink flowers,
‘Pinkbud’ — pink flowers,
‘Purple Leaf’ — purple young foliage,
‘Silver Cloud’ — leaves have white variegation,
Cercis canadensis var. alba — white flowers, blooms late,
C. canadensis var. texensis ‘Texas White’ — superior foliage,
C. occidentalis, California Redbud — found in Utah, Nevada, California and Arizona.
C. reniformis ‘Oklahoma’ — superior foliage substitute for Eastern Redbud in non-irrigated areas,

 


Unfortunately, Eastern Redbud is subject to many liabilities. Its functional life is 10 to 20 years in urban landscapes due to a combination of urban stresses, diseases, and pests. The tree is prone to trunk canker, heartwood rot, verticillium wilt, and scales, any of which can be fatal. It is also prone to storm damage with advanced age due to leaning and heartwood rot.


However, after a long hard winter, its beauty in spring provides a welcome that warms the heart of people everywhere.


 


Len Phillips can be reached via e-mail at lenphillips@on-line-seminars.com


 


Sources

Dickson, James G.. “Cercis canadensis,” USDA Forest Service, Silvics Manual, Volume 2, no date.
Gilman, Edward F. and Dennis G. Watson “Cercis canadensis, Eastern Redbud,” USDA Forest Service Fact Sheet ST-145, November 1993
The Ohio State University, “Cercis canadensis,” Plant List, OSU website, 2008
The photos attached to this article are taken from the Eastern Redbud in the author’s yard.

 


About the Urban Tree of the Year Selection


The Society of Municipal Arborists (SMA) conducts the Urban Tree of the Year competition to illustrate the importance of selecting the right tree for a planting site. The intent of this annual selection process is not to indicate that this tree is the perfect tree that can grow anywhere, but is to make municipal arborists aware of this tree and they should use it if they have a site suitable for it. The Urban Tree of the Year competition also provides extra publicity for excellent trees that should be used more often.


[Editor’s Note: Arbor Age magazine and author Len Phillips have no role in the selection of the Urban Tree of the Year, and are merely reporting this year’s selection, as well as supporting details and observations about the selection, here.]


 


Eastern Redbud


Botanical Name: Cercis Canadensis
Common Name: Eastern Redbud
Family: Leguminosae
Parentage: Native to North America
Height: 15 to 30 feet
Spread: 15 to 25 feet
Form: Round, irregular outline
Bloom Period: Spring flowering; very showy
Flower: Lavender, pink, magenta, purple, or white
Fruit: Brown pod, 1 to 3 inches long
Summer Foliage: Green
Autumn Foliage: Yellow
Winter Color: No special winter interest
Bark: Bark is thin and easily damaged from mechanical impact
Habitat: Tree grows in part shade/part sun, become less shade tolerant with age
Trunk: Usually multiple trunks, can be trained to single stem
Hardiness Zone: 4B – 9A
Growth Rate: Fast in youth moderate with age
Pest Problems: Borers attack the trunk of older and stressed trees, low disease resistance and short life
Storm Resistance: Susceptible to breakage at the crotch due to poor collar formation or the wood itself
Salt Tolerance: Poor
Planting: Transplant B & B or container
Pruning: Prune to develop strong structure, will require pruning for pedestrian clearance beneath the canopy
Propagating: Seed or grafting onto seedlings
Design Uses: Medium texture, container or above-ground planter; large parking lot islands, if used for a street tree, the tree lawn should be more than 6 feet wide
Other Comments: No significant litter problem, not particularly showy except in bloom, not good as a street tree
Availability: Generally available in most nurseries

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