March 2022 - Eastern Redbud

Common Name: Eastern Redbud.  May also be referred to as American Redbud.   

Botanical Name: Cercis canadensis

Native Range: Southern and central regions of eastern North America, with New Jersey on the northeastern edge of its native range.  In Hardiness Zones 4 to 9, grows beyond its native range in at elevations below 2,200’. 

Height: Usually reaches 20’-30’, but may grow as tall as 40’. 

Spread: 25’-35’. 

Form:  A small, deciduous, understory tree.  When young, has an upright vase growth habit.  Grown in the open, will develop a broad rounded to flat-topped crown with handsome, gracefully ascending branches.  May be multi-trunked.  Tree and shrub expert Michael A. Dirr writes: “In my opinion one of our most beautiful native trees.”

Growth Rate:  When young, redbuds grow quickly, 4’ to 6’ per year. Thereafter they have a medium growth rate of 7’ to 10’ over 5 to 6 years.

Sun:  Grows in full sun to partial shade, although the best flowering will be in full sun. 

Leaf Description: Alternate, simple, broadly heart-shaped leaves, 3” to 5” across, with untoothed margins, on a 2” to 5” petiole.  Emerging leaves in spring are reddish-purple and become a lustrous dark green by summer. 

Fall Color:  Leaves are yellow to greenish-yellow in fall.  

Flower Description:  Redbud is one of the first trees to bloom in early spring (March or April). Their rose-purple pea-like flowers, each up to a ½” wide and on a ½” stalk, blossom in clusters of 4 to10.  Even before the tree’s foliage emerges, profuse inflorescences burst forth throughout the tree along bare twigs, main branches, and older trunks. 

Fruit:  The flowers mature to flattened bean-like seedpods, 2” to 4” long and ½” wide.  Each pod has 6 to 12 seeds.  Initially pink to dark red-purple, the seedpods turn brown and dry, and hang conspicuously in dense clusters on the tree through fall into winter.

Bark Description:  Young twigs are lustrous reddish brown and speckled with lighter colored lenticels.  Main trunks become grayish-brown to nearly black, divided by deep longitudinal fissures into narrow plates.  The surface separates into thin scales, and the fissures expose the cinnamon-orange inner bark.

Wildlife Benefit:  Redbud blossoms are rich in both nectar and pollen and provide a valuable food source for bees in early spring, a time when food is scarce. Bees that benefit include honeybees, bumblebees, mason bees, cuckoo bees, long-horned bees, mining bees, blueberry bees, and sweat bees. Redbuds are also host plants for the larvae of several butterflies and moths.  The caterpillar of the redbud leaf-folder moth (Fascista cercerisella) only eats redbud leaves.  Redbud seedpods can provide food for birds throughout the fall and winter.

Tolerates:  

• Tolerates clay soil but does best in moist, well-drained deep soil. 
• Tolerates drought but does better with regular watering.
• Tolerant of juglone, so can be grown under black walnut.

Possible Insects:  Redbuds have few insect pests other than scales, which suck the juices out of their leaves.  A scale infestation does not typically harm a healthy tree, but can further weaken one that is already stressed.

Possible Disease:   Canker can be a problem for redbuds and typically limits their life span to about 25 years. The fungus that causes canker enters environmentally stressed trees through openings caused by mechanical injury or insect damage. Watering during periods of drought and avoiding wounds to the tree helps prevent canker.  Otherwise, redbuds are not prone to disease, but can incur verticillium wilt, dieback, leaf spots, mildew and blights.   

Uses:  

• An ornamental.   May be used as a specimen tree or in small groups in lawns, shrub borders, or along patios. 
• Attractive in naturalized settings such as woodland margins, stream banks, old fields and open woodlands.

Where to be found on municipal property:  A mature specimen may be found in Marquand Park.  To locate, consult the map of the park’s specimen trees, displayed near the park entry off the parking lot on Lover’s Lane.  Look for the map just beyond the little children’s library.  The map key indicates that the “American redbud” is to be found at H, 3.  In addition, three newly planted redbuds can be viewed around the basketball court in Quarry Park.  Redbud trees can also be seen at the entryway to the Billy Johnson Mountain Lakes Nature Preserve, and also down by the lake along the woodland edges that border Mountain Lakes' House. 

Additional Facts: 

• The name “redbud” refers to the tree’s winter appearance.  Thoughout the coldest months of the year can be laden with purplish-red buds.
• More than a dozen cultivars are commercially available, including some with white blossoms.
• Redbuds will not thrive in full shade or in wet or poorly drained soils. 
• They develop a deep taproot so do not transplant well.  Best to plant, in spring or fall, when young and leave undisturbed. 
• Deer tend to avoid this plant.
• The flower is edible and is often used in desserts.
• Cercis canandensis var. alba is a naturally occurring white variety
• Cercis canadensis ‘Forest Pansy’ is a common cultivar with purple leaves
• Cercis canadensis ‘Ruby Falls’ is a common weeping cultivar 
• See how much your redbud is worth https://www.arborday.org/calculator/treeInfo.cfm?zip=08540&city=PRINCETON&state=NJ&climatezone=South

References

Missouri Botanical Garden https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=h550

Martine, Christopher, Trees of New Jersey and the Mid-Atlantic States, Forest Education Resource Center, NJ Department of Environmental Protection, 4^th Edition, 2000.

Dirr, Michael A., Manual of Woody Landscape Plants, Their Identification, Ornamental Characteristics, Culture, Propagation and Uses, 5^th Edition, Stipes Publishing L.L.C., 1998.

Lady Bird Johnson Wildflower Center https://www.wildflower.org/plants/result.php?id_plant=BENI

Penn State Extension, “Eastern Redbuds Support Early Pollinators” https://extension.psu.edu/eastern-redbuds-support-early-pollinators   

Trimboli, Shannon, ”Redbuds – A Beautiful and Early Source of Nectar and Pollen,” posted on March 14, 2017 https://shannontrimboli.com/redbuds/ 

Cullina, William, Native Trees, Shrubs, & Vines, The New England Wild Flower Society, 2002.

Taylor, Patricia A. Taylor, “Redbuds' 15 Minutes Are Ticking,” The New York Times, April 18, 2004.

University of Wisconsin-Madison, Wisconsin Horticulture, Division of Extension, “Eastern Redbud, Cercis canadensis” https://hort.extension.wisc.edu/articles/eastern-redbud-cercis-canadensis/   

Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C. http://bonap.net/MapGallery/County/Cercis%20canadensis.png 

Kershner, Mathews, Nelson, & Spellenberg, Field Guide to Trees of North America, National Wildlife Federation, 2008.

Sandra Chen, February 2022