Not in the supermarket. Apple partisans (a real faction) often claim that the typical American grocer stocks no more than 12 varieties: Red Delicious, Gala, Fuji, et al.

Beyond that tiny set, Mr. Bussey said, “There’s at least 5,000 apples still out there, up to present-day breeding.” These are varieties that have been identified growing in one orchard or another.

The recent cider revival has yanked a few such antiquities back into the market stall. You won’t be drinking alone at a festival like the upcoming Franklin County CiderDays in western Massachusetts, where Mr. Bunker and friends will help propose a use for any apple you’ve got (Oct. 31 to Nov. 2). But if you’re hoping to get a taste of a particular heritage apple — say, a Knobby Russet, a Black Gilliflower or a Pitmaston Pineapple — the most expeditious plan is to plant a tree and wait five years for it to set fruit.

Mr. Bussey currently nurtures all of those apples, and 1,100 others, as the manager of the Seed Savers Exchange Historic Orchard here, one of perhaps a dozen major collections scattered across the country. The largest, which Mr. Bussey visited two years ago in Yoncalla, Ore., represents more than 4,000 apples and belongs to a former Alaska bush pilot named Nick Botner, who is almost 90 years old.

It’s an amazing number. Yet do the arithmetic and you realize Mr. Bussey has devoted thousands of pages and decades of research to documenting more than 12,000 apples that no longer exist and likely never will again. Many of them can be seen only as archival watercolors, created a century ago from the original apples by artists at the United States Department of Agriculture. Most of the 1,500 illustrations selected for the book will be published here for the first time in memory.

For all the information Mr. Bussey has exhumed about each vanished fruit, he said, “The only thing I can’t tell is what it tasted like. That’s totally unknown.”

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What if the trees aren’t gone but, rather, misplaced? This is the hypothesis advanced by Mr. Bunker, who grows 250 apples in his small orchard in Palermo, Me., and sells more than 100 of these through the Fedco Trees cooperative.