About two-thirds of the $4 billion apple industry is now concentrated in Washington State — and 15 varieties, led by the Red Delicious, account for about 90 percent of the market. But the past looked, and tasted, much different: An estimated 17,000 varieties were grown in North America over the centuries, and about 13,000 are lost. //

some old varieties have become available again, through small specialty nurseries like the co-op that Mr. Bunker helped start in Maine and through university agricultural programs. Commercial growers, however, said old apples had faded for a reason and were probably not coming back.

“They’re hard to grow,” said Mac Riggan, the director of marketing at Chelan Fresh, which has 26,000 acres of fruit trees, mostly apples, in central Washington.

Old varieties, Mr. Riggan said, either bruise easily, don’t store well or don’t produce enough apples per tree. And economic pressure is relentless. “Land costs money,” he said. //

A woman recently sent him a catalog from 1912 she had found in her attic. It listed more than 140 apple varieties then available in Washington. Documents from county fairs — what apples were offered for judging and won the blue ribbon — have provided another critical piece of evidence. //

On a recent morning at Steptoe Butte State Park, where Mr. Benscoter has focused his work, about a five-hour drive from Seattle, he hiked toward an Arkansas Beauty apple tree, perhaps the only one on the planet currently bearing fruit. The tree’s identity was confirmed this year after testing and tasting by scientists and food historians.

Finally, the tree came into view, standing alone in a clearing that overlooked rolling hills of wheat. It was about 12 feet tall and twisted with age. Mr. Benscoter hoisted up the chain saw he had carried out from his truck and pruned off some small branches, which will stimulate the tree to grow new shoots that can be grafted next year onto other trees. And so another relic from America’s past will live on.

He said he often wondered what the old farmers would think about his work, and about the trees that they pushed into the soil and toiled over before walking away in defeat.

“I think they would be glad that something they planted survived,” he said.