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‘A Kaleidoscope of Colors’: NC State Breeder Creates Winning Flame Thrower™ Redbud

Flamethrower redbud trees with a blue background
A field of Flame thrower™ redbuds, created by Dennis Werner. Photo courtesy of Alex Neubauer, Owner of Hidden Hollow Nursery in Belvidere, Tennessee

As a child in Pennsylvania, Dennis Werner would walk in the woods with a plant identification book and his curiosity in hand. Though many trees in the forest towered over him, the redbud caught his attention. Its buds happened to bloom right at Werner’s eye level, allowing him to peer closely and examine it. 

“I didn’t know anything about taxonomy or how plants were classified, but I’d find a leaf on a tree and I’d start paging through my book just to try to match it up,” Werner said. “And that’s how I learned about trees.”

While Werner has grown taller than some of these redbud’s branches from his childhood walks, his curiosity for the tree has remained constant. 

Man stands underneath a redbud tree
Dennis Werner stands by an Eastern redbud at the JC Raulston Arboretum.

For the past 24 years, he has bred redbuds, creating five different varieties to complement his robust research efforts as a professor in the Department of Horticultural Science at NC State. Now a Distinguished Emeritus Professor, Werner’s recent redbud variety, the Flame thrower™, won first place for Plant of the Year at the 2021 Royal Horticultural Society’s (RHS) Chelsea Flower Show

The prestigious RHS Chelsea Flower Show is held in London and attracts international attention. This year, the event was capped at 142,000 people and staged over seven days instead of the usual six days. Its guests included members of the royal family, according to Jill Otway, the plant committee manager for the RHS. 

Chelsea Flower Show Flamethrower redbud
The Flame Thrower™ redbud at the RHS Chelsea Flower Show. Photo Credit: John Grimshaw

Werner’s Flame Thrower™ redbud (marketed as Eternal Flame™ in the United Kingdom) was deemed the Plant of the Year by a vote of approximately 60 horticultural experts, including members of the RHS Plant Committee, Otway said.  

“This is a crowning glory for his career,” said Director of the Yorkshire Arboretum and an esteemed author John Grimshaw. “His product will now be very widely grown, and very widely recognized.”

Werner credits the JC Raulston Arboretum for fostering his interest in redbuds as a professor, and as a former director of the arboretum. 

“The JC Raulston Arboretum here at NC State has historically always had a great collection of redbud varieties,” Werner said. “When I would walk the arboretum, I was always taken with all of the interesting variations in redbuds, in terms of not just flower color, but also foliage characteristics.”

These arboretum walks sparked Werner’s interest in breeding new varieties of redbuds from existing species. What would happen if the leaf color from one redbud could be crossed with the color from another? Like a painter mixing shades on a palette, Werner became curious about the nuanced possibilities with breeding redbuds. 

A pathway at the arboretum surrounded by trees
A pathway at the JC Raulston Arboretum where Dennis Werner walked to look at redbuds.

He has created multiple redbud varieties, including Ruby Falls and Merlot. However, the Flame Thrower™ has attracted the attention of international enthusiasts and experts alike. The Flame Thrower™ is aptly named for its leaves that emerge in a range of bright shades, beginning with a “really deep red,” Werner said. 

“As the foliage develops and begins to mature, the tree exhibits a combination of colors, including red, purple, burnt oranges, bronze, and gold,” Werner explained. “Hence, a kaleidoscope of colors are expressed during the growing season.” 

As these plants started flowering at the Sandhills Research Station, they attracted the attention of a variety of individuals, even those who did not work on ornamentals, Werner said. 

“I knew I was onto something when a soybean breeder or a plant pathologist would come up to me and say, ‘What is that tree up there on the hill? What is that, with the multiple colors on it?”’ Werner said. 

Close-up photograph of leaves from Flamethrower redbud
Leaves of a Flame Thrower™ redbud, created by Dennis Werner. Photo courtesy of Alex Neubauer.

While Werner had a sense he had created something special with the Flame Thrower™ redbud, he explained that there are multiple steps to prepare a plant for commercialization. 

For example, one thing that Werner had to tinker with was the expression of gold in the plant. Gold can be a finicky thing, he explained. If the redbud did not express enough gold, the range of leaf colors could be limited. However, if the redbud expressed too much gold, its leaves could be scorched by the sun. 

Since the Flame Thrower™ redbud is an ornamental, and it is purchased by everyday people to decorate their surroundings, this scorching could detract from the value of the plant.

“I would say 90% of what we put out in the field got discarded because they were just showing too much scorching,” Werner said. “And that’s common in gold leaf plants. There are a lot of gold-leaf forms that tend to suffer when they get in full sun.”

To prevent this scorching, Werner chose Flame Thrower™ redbuds that exhibited an optimal amount of gold expression to thrive in sunny states, like North Carolina. These redbuds were then grafted onto redbuds at a partner nursery in Tennessee, where they could be multiplied in mass quantities. 

Once Werner had successfully worked with his partners to finish the creation of the Flame Thrower™ redbud, he worked to commercialize it, so that it could be sold to everyday people and be available at garden shops.

As a plant breeder, you hope to create something that is unique and distinctly different from anything that’s in the industry at the time.

Flame Thrower™ was developed during an industry-sponsored research program with Star Roses and Plants, who had the first opportunity to license any intellectual property created during the program. In 2018, Werner disclosed the new tree to the Office of Research and Commercialization, which then reported the disclosure to Star Roses and Plants. 

NC State and Star Roses and Plants entered into a license agreement, allowing Star Roses and Plants to become the sole partner and exclusive licensee for production, marketing and sales of the Flame Thrower™. 

After a plant is licensed, NC State receives a royalty for each one sold. Part of that royalty goes back into the Department of Horticultural Science, which is invested into future research, and part of it is paid to the plant’s inventor. 

However, the recognition Flame Thrower™ has received is invaluable, according to Rob Whitehead, the germplasm agreements associate in NC State’s Office of Research Commercialization

“There is a financial benefit, but with Flame Thrower™, perhaps the biggest benefit is being recognized internationally as a superior variety,” said Whitehead. “That reflects very well on the university, our plant program and Denny in particular.”

Winning the Plant of the Year award at the prestigious RHS Chelsea Flower show can propel sales of this plant for years to come, according to Grimshaw. 

Man stands next to a redbud with gray sky in background
Dennis Werner stands next to a Flame Thrower™redbud.

As more individuals from across the world plant the Flame Thrower™ redbud in their gardens and businesses, Werner is interested to discover how the plant’s color expression varies with environmental changes in other parts of the world, from temperature to rainfall. 

In addition to improving scientific understanding, Werner said it is gratifying to watch others find joy through planting trees and shrubs.

“We live in somewhat of a chaotic society,” Werner said. “As individuals, we have to find ways to find peace and calm in our lives.”

For Werner, appreciating the beauty of plants has been a constant for him throughout his life. 

The forest Werner used to walk in as a child in Pennsylvania has since been turned into a parking lot. However, recently planted at the edge of the JC Raulston Arboretum, is a Flame Thrower™ redbud, soaked in morning dew and awaiting spring to show its kaleidoscope of colors.