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2010 Urban Tree of the Year

Eastern Redbud

Eastern Redbud (Ceris Canadensis) was selected as the Society of Municipal Arborists (SMA) Urban Tree of the Year. 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 siliquastnum.

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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 call Eastern Redbud its state tree.

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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 or three weeks. The flowers can be found on the trunk or branches, but most are found on two year old twigs.

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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.

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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 slightly more plump and in clusters along stems, branches and trunks.

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The trunk is either single-trunked and low-branching,or multi-trunked and shrub form. The exterior bark is grown 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.

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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.

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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 and 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.

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Eastern Redbud grows best in partial shade especially 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.

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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.

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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.

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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.

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

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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 'Tesas White'--superior foliage.
• C. reniformis 'Oklahoma'--superior foliage, white buds/flowers.

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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.

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