The Science of Paulownia

by | Jan 28, 2019

Dr. Nirmal Joshee is a scientist at Fort Valley State University in Georgia who has been studying Paulownia (aka the Empress tree) for 14 years. We were excited to meet him and his team, who have been given a large grant to further our understanding of the properties of Paulownia.

“Almost every scientific study of Paulownia has been done in China and we have no English translations,” explained Dr. Joshee. “My team is conducting scientific research here in Georgia, so that we can better understand the remarkable properties of this tree.”

 Dr. Joshee took us to see their plantation of 2600 trees. His team planted the trees ten years ago and watched to see what would happen.

“We planted the trees into the soil and left them to grow naturally. We didn’t fertilize or water them – we wanted to see what they would do if we didn’t give them any care and attention at all. As you can see, they grew really well!”

We look up to the sky at the towering branches of trees that are 30 feet high. The trees are a mix of Paulownia elongata and Paulownia fortunei, the same species that World Tree uses. 


Regenerating the Soil

The first thing that Dr. Joshee tells us about is the soil. “See the soil over there, see how orange it is? That is typical hard clay Georgia soil.” We look over at a big stretch of orange soil with nothing much growing in it.

“Now look at this,” he bounces up and down on the ground beneath the trees. The soil is deep, rich black/brown and is crumbly. He explains that the trees have regenerated the soil, providing nutrition for other plants.

The reason for this is that the leaves of Paulownia are nitrogen-fixing. The leaves pull nitrogen out of the air and store it in their cells. Nitrogen is the main ingredient of fertilizers, which means that when the leaves fall to the ground in winter, they provide a natural fertilizer. No wonder the soil is looking so healthy. 

Is the tree invasive?

One of the questions we get asked all the time at World Tree is about the invasiveness of the tree. We were curious to hear what Dr. Joshee had to say about that.

We asked him: “What do you say to people who think the tree is invasive?”

Dr. Nirmal smiles, “The USDA visited our plantation and asked the same question. The answer is no, and here is the proof,” he waves his arm at the trees. “We planted 2600 trees here ten years ago and then watched to see what would happen. The trees have not reproduced, not even one single shoot. If they were invasive, we would have seen trees everywhere.”

He makes a good point: If Paulownia was invasive we would see it all over the United States when In fact, most people have never seen or heard of the tree before.


The Paulownia Buzz: Empress Tree honey


The Empress tree produces beautiful pink-purple blossoms, that have a powerful vanilla-jasmine scent which honey bees love. The honey is delicious, but it turns out that it has an extraordinary secret property that no-one knew about until now.

Dr. Joshee’s team placed 20 hives around their plantation and stood back to see what happened. “It was amazing,” explains Dr Joshee, “The whole plantation came alive with the sound of the buzzing.”

Each hive produced 15-20 kg of honey, some of which they took back to the lab for further study. And here’s where things get very interesting.

“We discovered that Paulownia honey contains no sucrose,” explains Dr. Joshee. 

This means that the honey is potentially suitable for diabetics. Very few types of honey in the world have this property.

Paulownia medicine

Paulownia, it turns out, is not just a pretty tree. The Fort Valley team is studying the medicinal properties of the flowers and leaves which have a long history of being used in Chinese medicine.

The leaves have anti-biotic properties and are especially good at treating upper-respiratory problems. It is also used in Chinese medicine to treat seizures and is even said to be a cure for baldness.

“There is so much to know about this tree,” says Dr. Joshee, who has just been given a grant to continue his research. 

We look forward to hearing more from his team over the next few years.