COLUMBIA — In March, Missouri’s largest bur oak tree, located south of Columbia near McBaine, received some expert forestry care in an attempt to slow its decline into old age. The tree is estimated to be between 200 and 400 years old. Now, the process of grafting is being used to propagate the state’s champion bur oak, also known as the McBaine tree.
In order to preserve the DNA of the tree, wood samples were taken from the tree’s newest branches to be grafted onto seedlings at MU’s Horticulture and Agroforestry Research Center in New Franklin.
Grafting is the process of encouraging the tissues of one plant to fuse with those of another, creating one conjoined plant. The wood samples from the McBaine tree were grafted to seedling bur oaks April 14. After about two weeks, 22 of the 28 grafts had been successful. They are now growing into healthy young copies of the McBaine tree.
There are many reasons why grafting a plant instead of growing offspring from its seeds is the most effective way to preserve a plant’s DNA, said Mark Coggeshall, an agroforestry research analyst for MU.
“A seed is a result of meiosis between a mother and a father plant,” he said. “If you take seeds from that tree, you will have approximately one-half of the genetic makeup of the tree.”
Instead, grafting a sample of the tree to a younger tree preserves the exact genetic makeup of the original.
Another benefit of grafting is that the plants produce seeds or fruit more quickly. Grafted trees can produce seeds before they are one year old, Coggeshall said.
“This is a little one-year-old stick, but it came from a very, very, very old tree,” Coggeshall said, pointing to one of the grafted trees. “And the result is that it tends to produce seeds quicker because it is more mature.”
This is not the first time the Mcbaine tree has been subject to grafting, said the owner of the tree, John Sam Williamson. A sample of the McBaine tree was grafted to one of its offspring grown from seed several years ago. It is now growing in Williamson’s yard.
Chris Starbuck, a horticulturist at MU, said the McBaine tree has survived a lot of damage and its DNA is worth preserving.
A flood in 1993 put the tree under nine feet of water for about six weeks, Starbuck said, which would have killed most trees. During this time, it was struck by lightning, blowing out a piece of the bark.
“If you look at the trunk now, it’s not obvious where it occurred, which means the tree had enough energy and vitality to cover that up,” Starbuck said.
The tree was also set on fire once, Starbuck said, creating a large hole in the tree.
The owner, John Sam Williamson, has since filled in the hole with concrete.
Williamson added to Starbuck’s list of things the tree has survived.
“People have cut bark off it, shot at it, carved on it and occasionally leave trash around the tree,” Williamson said. “Generally, though, most people actually pick up a little around the tree.”
Starbuck is still not sure what will happen to the successful grafts from the McBaine tree.
“I expect one will end up at the new courthouse when it’s built,” Starbuck said. “We’ll try to place them where they are most appropriate.”