GRAND FORKS — A pair of North Dakota scientists have secured a patent on a variety of a white mulberry tree, and it is now for sale at nurseries in the state and beyond.

Michael Kjelland, a professor at Mayville State University, and Jim Walla, a retired North Dakota State University research scientist, secured the patent on the prolific berry-producing tree in 2018. It’s been a years-long project for the pair that is now bearing fruit.

The tree is called the “Trader” mulberry, the family name of the man who, as the story goes, brought it to North Dakota from Germany about 130 years ago. Sales of the variety have done well, with about 4,000 trees having been sold. Walla runs Northern Tree Specialties in Fargo, and there’s a wait to get one.

Through a license agreement, the pair made the tree available for larger nurseries, like Minnesota-based Bailey Nurseries and Michigan-based Hartmann’s Plant Company, and it’s also available from a small nursery in Vermont. With the waiting list at Walla’s Fargo operation, Kjelland said he had to place an order from a larger nursery for a person who wanted one – only to find they were out of stock there as well.

“It turns out they were sold out so I can't even buy any of my own tree variety,” Kjelland laughed. “It's kind of funny but I mean, the silver lining there is great – everybody wanted them. …”

For Kjellan, the Trader tree has been a long-running project now brought to fruition. He got interested in the tree about 25 years ago, when he tried some mulberry jelly made by Mildred Trader, a friend of his grandparents. He was hooked. He asked for a cutting and worked with Walla to propagate it, and then on the patent.

The Trader Mulberry is a hardy variety that does well in North Dakota’s climate. According to Trader family tradition, it was brought to the state by William Trader in the early 1890s. Walla said that over a 30-year period, Trader moved around and apparently spent time in Wisconsin, North Dakota and South Dakota, before settling near Oriska, N.D., where the original tree remains today. Trader supposedly took the tree with him wherever he went, and the now-patented Trader mulberry trees are clones of the original.

“For him to propagate it and move it every place he was over those 30-some years would take special ability, and that would have been a rare thing,” Walla said.

Curious people who might want to plant a Trader mulberry need to be aware of its size. Walla said it can get to be 35 feet tall, with a 30-foot-wide canopy, which may make it a bit too big for some backyards. The tree, however, can be pruned to the size of an apple tree.

The fruit resembles a blackberry, though the seeds can be eaten. It can leave a stain on a person’s fingers, if not other objects, so placement is important. As for the taste, Walla said it is sweet, when left to ripen to the point where it falls off the branch when touched. Aside from sweet, he said it’s tough to describe the taste.

“I can't say it tastes like a strawberry, a blackberry or a raspberry,” Walla said. “There's nothing else that I've ever tasted that tastes like a mulberry.”

And Walla would know. He grew up in Nebraska where mulberry trees are more prolific. They grow in North Dakota too, but are hybrid varieties that grow poorly and don’t produce great fruit.

The Trader tree, a pure white mulberry variety, has the genetics that let it flourish here. It is meant to be planted in the northern tier of U.S. states, or the southern tier of Canadian provinces.

This isn’t the first time Kjellan has worked with trees and plant-based projects, though the Trader tree project was done outside of his work at MSU. People might be more familiar with his work as a paleontologist – along with an excavation partner he discovered a fossilized triceratops skull in 2019.

But Kjellan also teaches botany, and has collaborated on plant-based research projects before at Mayville State, such as using wheat bran in cancer intervention. Another project involved using wheat bran for industrial purposes, such as thermoplastics.

He’s working on a state Department of Agriculture grant for another tree-related project, one that could offer some hands-on experience for his students.

“If we do get that grant then we'd involve some students from Mayville State University. That's the idea behind it,” Kjellan said.

Though he’s one of the Trader tree’s patent holders – he and Walla receive a dollar per tree from nurseries that sell them – Kjellan said it was never about the money.

“It was about trying to do something unique,” he said. “I like to try and get different varieties growing here that can be beneficial for both humans and wildlife.”