My grandfather often tells me a tale of a tree.

It was a chestnut tree, he claims, that soared high above his boyhood farm. The trunk was so large, the tale goes, that it took a day and a half to walk around it.

Was it hyperbole? A tall tale between his a grandpa and his grandson? Or was there a glimmer of truth to the story?

In my younger days, I was certain it was just my grandfather's way of teaching me about the good ol' days -- kind of like walking to and from school through eight feet of snow, uphill both ways. But the older I get, the wiser I become.

These days I know a heck of a lot more about the great American chestnut tree. And the more I know about this magnificent species of tree, the more I realize my grandpa's story may not be all that far-fetched. In his day, there were some big trees.

The American chestnut is an invisible piece of the nation's history. Two centuries ago, the massive trees dominated the landscape of the Eastern seaboard. Reaching heights of 100 feet, they were the king of the forest.

But 1904 marked the beginning of the end for the American chestnut. That's when a fungus carried here from Asia entered American forests. Over the next half century, the ensuing blight killed billions of chestnut trees. Today, just a few highly protected groves of the majestic trees still stand. They're under constant attack from the invasive fungus.

There is good news, however. Scientists are closer than ever to introducing a strain of chestnut tree that is tolerant of the killer fungus. Their goal is to create a tree that looks like an American chestnut, but has the disease tolerance of a Chinese chestnut.

How they are accomplishing their goal is an interesting, and oddly simple, scientific process. The American Chestnut Foundation and scientists from a variety of organizations across the nation have taken the idea of "survival of the fittest" to an extreme.

For the last 30 years, those folks have been crossbreeding Chinese and American chestnuts. It's a painfully slow process. Once the hybrid seeds are planted, the scientists must wait to see which trees are the strongest and, most important, show the best resistance to the deadly fungus. The trees with the best traits are then bred to create, what scientists hope, is an even stronger strain.

The trees that don't make the grade are destroyed.

Right now, the breeding program is onto its sixth generation of trees. With each generation stronger than the last, the scientists are closer than ever to what they believe will be a fully resistant American chestnut tree. When those folks reach their goal, they'll be able to bring back a great slice of American history.

I may never get to tell my grandson about taking a day and a half to walk around one of these beastly trees. But thanks to the hard work of a group of volunteers and scientists, my grandson may very well get to see Penn's Woods again filled with American chestnuts.

That'll be another tale worth telling.

-- Andy Snyder writes about the outdoors for The York Dispatch. He can be reached at sports@york