Nearly four billion American chestnut trees once grew in the eastern United States, dominating forests from Maine to Florida. Wood logged from the massive trees helped build everything from homes to railroad ties and its chestnuts fed animals and people, but then, about a century ago, disease wiped out virtually all the trees.

"Every year it produced bushels of nutritious chestnuts, supported wildlife like we've never seen since. And it also sustained the people," said Rex Mann, a retired forest ranger and volunteer with the American Chestnut Foundation.

When a type of fungus named a blight was brought to the U.S. through trade at the turn of the 20th century, it decimated four billion trees in just five decades. Those that remain in the wild cannot reproduce on their own.

Now, for what researchers say is the first time in American history, a functionally extinct tree species could be restored, CBS News correspondent Chip Reid reports.

"We as a science team are trying to develop an American chestnut tree that has enough blight tolerance that it could survive in the forest," said Tom Saielli, the mid-Atlantic regional science coordinator at the American Chestnut Foundation.

Researchers at the foundation are breeding the American chestnut with the Chinese chestnut, which is resistant to the blight. After the trees are bred, their burs, which house the nuts, are harvested. Inside each bur are two or three chestnuts that will be planted, just one step in a long, complicated process that the foundation hopes will eventually lead to a blight-resistant American chestnut tree.

But, before they are planted and bred again, the burs must be sorted. Then, the viable nuts will be planted and injected with the blight to see which ones survive. The young trees that do well will be bred again.

"Tell me why it is so important to save the American chestnut tree," Reid said.



"Well, it was a way of life in the Appalachians and the eastern U.S. forests," said Lisa Thomson, president and CEO, the American Chestnut Foundation.

The mighty American chestnut also bears rot-resistant timber, which provided homes and industry to the nation's heartland, and with it, hope for those who had little.



"Those people were poor. In the fall of the year, they would gather chestnuts by the sacks full, carry them down to the country store, and swap them for shoes for the kids," Mann said. "There were trainloads of chestnuts going to all the major cities. And people bought them and roasted them on the street."



Now, chestnuts roasting on open fires across America are of the larger, less sweet European and Asian varieties.



"We want a tree that's competitive in the forest, grows tall and replaces the American chestnut in that great form and timber quality," Saielli said.



If researchers can rescue the tree, the American chestnut could serve both as a model for protecting other vulnerable plant species from insects and disease and as a weapon against climate change, capturing more carbon from the air thanks to its larger size.



"We're blazing a trail for how people who care about this can restore the other trees we're losing. I think that's really the big story," Mann said.

