Conjoined branches rare but explained

Earlier this week, Eh? asked readers if they knew how two trees could join together by one branch. We ran a photo of two box elders that appeared to be connected by a common branch on the property of Vickie and Dennis Berg of Carlton.

It’s called grafting, St. Louis County forester Bill Hakala said. It’s common in nurseries and especially among fruit-tree growers to graft hardy trees with trees known for good fruit. But it also happens in nature, Hakala said. He sees it occasionally in his job in the woods.

So does Bob Olen, St. Louis County Extension agent. The two tree experts said the branches, especially when young, can rub together in the wind, scraping off the external bark and exposing the reproductive tissue inside the branch. Once joined, the branches heal back up.

“It’s not common, but it certainly happens out there,” Olen noted.

Many trees do the same thing all the time — graft on to one another — only through the root systems underground, where they can’t be seen, the tree gurus noted.

Now you know.