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Creating a New Hue

Chemistry Research Project Turns Hydrangeas Yellow and Lisianthus Blue

 
Last month the plant coloration project was featured on WSLS TV 10 in Roanoke, Va.  

Research by VMI’s chemistry department is producing cut flowers in shades unknown to nature. Yellow hydrangea and blue lisianthus blooms are the most successful products that have come from studies of how the application of metals can change the color of blooms.

In both cases, molybdenum was the key ingredient, making a white hydrangea bloom yellow and a purple lisianthus bloom blue.
Altering soil chemistry to effect a change in bloom color is nothing new, as gardeners have traditionally used aluminum sulfate to ensure their hydrangeas have a blue hue.

Col. Henry Schreiber, professor of chemistry, along with cadets Corinne Lariviere ’13 and Blaine Groat ’13 are working to discover what metals react with the pigmentation processes of particular plants.

“People have been trying to get what you don’t have naturally,” said Schreiber, who has been working on producing yellow hydrangeas for about seven years and has studied the reactions of other metals as well, including iron and uranium. The project was funded in part through a grant from the Association of Specialty Cut Flower Growers.

Having found that molybdenum produced solid results, the work going forward consists of fine-tuning the process.

“It’s about carefully manipulating the concentration of the metal. Ideally we want to make a blue bloom before it even develops, so we’re adding molybdenum to the soil in hopes of the bloom developing as a natural blue bloom,” said Lariviere.

Blue lisianthus blooms are currently being produced by cutting the purple flowers and placing them in vases containing molybdenum solution. Getting the plant to produce a blue flower to start with is a matter of maintaining the correct concentration of molybdenum in the soil over time.

“There are all sorts of variables in terms of how to optimize pigmentation,” said Schreiber. “If the solution is too strong, the plants will die; if it’s too dilute, they won’t have enough color, and some varieties are easier to color than others.”

To complicate matters further, pigments respond much differently to metals in the test tube than they do in the plant. For example, mixing the hydrangea pigment with molybdenum in the test tube produced a blue hue rather than the yellow found when molybdenum was added to the plant.

That complexity presents a challenge and an opportunity for cadets.

"This research involves so many processes and ideas and ways of thinking,” said Lariviere. “We’re not just in the lab working on the bench. We’re going out into the field, and it’s always something new and interesting.”

Lariviere will graduate this December and is looking forward to studying chemistry in graduate school.

“This has been a lot of fun,” said Lariviere. “When I first started, I wanted to go to medical school, but I really got into chemistry and now I love it.”

Since the summer following her 4th Class year, Lariviere has been working on altering the pigmentation of flowers. She presented the results of that research at the International Hydrangea Symposium in Angers, France, alongside experts from around the world.

“I got to go to France this summer to present on the yellow hydrangea, and that was a pretty incredible experience,” said Lariviere. “I was definitely the youngest one at the conference. That was a little bit intimidating to say the least.”

–John Robertson IV  

–VMI–