2017-08-09 / Columns

My Terrific American Chestnut Tree!

by Dan Stiles Wildlife Biologist

The truth is, my five-yearold American restoration chestnut tree is not exactly a “pure” American chestnut. It is 1/16th Chinese chestnut, the parts that hopefully contains the genes that are resistant to the chestnut blight, and the other 15/16th are pure American chestnut genes. But nevertheless, this summer my very young tree began to grow numerous burs (maybe 50) that were heavy enough to weigh down the lower branches close to the ground. Burs are extremely prickly, green colored, protective shelters that contain several maturing chestnut seeds.

The interesting, hard-to-believe part of this story is that it takes two chestnut trees to produce viable seeds, even though a single tree produces both female flowers and male pollen. My tree produced many hundreds of catkins this spring, so much so that the whole tree looked white from a distance. But, come to find out, these catkins that produce pollen are not able to fertilize the female flowers developing right alongside them. I’m told that if they did, and it happens rarely, the resulting seeds would not germinate, and if a few did, the seedlings would be of inferior quality.

In the fall, these prickly burs split open and the mature chestnut seeds fall out to whatever fate awaits them. A few lucky ones fall on fertile ground and germinate almost immediately, putting down a root that will become a chestnut seedling the following Spring. Like everything else in the natural world, the vast majority of excess chestnuts are lost, if you can call it that, consumed by many wildlife species, notably deer, bears, turkeys, raccoons, squirrels, mice and many other critters, as well as people who gather them to roast!

Back to my terrific chestnut tree. The big question is, are the seeds within all these burs fertile? Where did the pollen come from? Might these seeds have been fertilized by the pollen from my same terrific tree? If I were to wait until fall and examine the fully developed seeds, would they be healthy looking or dried and shriveled? Dried and shriveled would mean they were not capable of producing healthy seedlings.

So, being excited and impatient, with heavy leather gloves and a new razor blade, I cut open one of the burs. I was delighted to find that there were three moist, fleshy chestnut seeds within the bur, so the pollen that fertilized them must have come from another chestnut tree in the vicinity. I’m told the chestnut tree or trees might be as far as a quarter of a mile away. Honey bees, bumble bees, butterflies and all the other pollinating insects are strongly attracted to flowering chestnut trees, and the pollen is moved from one flowering trees to another by these pollinating insects.

Chances are that my tree was pollinated by a Chinese chestnut somewhere in the vicinity. I have no idea where it might be, but obviously pollinating insects have located it. There is a distant chance that the source of the pollen is an American chestnut, but common sense suggests that probably is not the case.

At any rate, this fall I’ll gather the mature burs and shake out the seeds. Most likely the seeds will contain a few more Chinese genes than American, but perhaps (and hopefully) some of those genes will be the Chinese chestnut’s keys to resisting the chestnut blight. We live in hopes, for sure!

And yes, I intend to plant every one of these seeds on our property in Morgan County. Growing a regular forest of chestnut trees sounds like a task I’ve always wanted to do!

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very interesting how the

very interesting how the Asian genetic material is resistant to the blight. this could mean that the blight itself originated in Asia and the American Chestnut version never was exposed to the material til it was some how transported to our hemisphere perhaps during shifting weather patterns and the melting of ice from glaciers releasing the spores that attack native North American Chestnut Trees