The Gunnery, a private school in Washington, has an unassuming almost 20-foot tree growing out of a rock outcropping by the Tisch Schoolhouse parking lot.

What is unique about the tree is it is a famed American chestnut, a species that once dominated the hardwood population in eastern America and was memorialized in “The Village Blacksmith” by Henry Wadsworth Longfellow.

This fall, in time for the opening of school, the tree has produced fruits of the form of two spikey, green nuts.

“Most people alive have never seen a fruiting American chestnut,” said Glenn Hartz of the maintenance department, who has cared for the tree for 31 years.

“The chestnuts we all have been ‘roasting on an open fire’ are from either a Chinese or a European variety which is resistant to the blight,” Hartz said.

“For now, the tree is still vulnerable to blight and should be watched but not touched,” he noted.

The American chestnut tree was hit by a blight in 1904 that reduced the viable trees from close to 3 billion in their natural range to a mere 100 or so mature trees (those with a trunk diameter over two feet) in this country.

The American chestnut provided most of the ships’ masts before the steam engine was invented, a fast, straight-growing tree which often reached more than 98 feet.

The Gunnery’s American chestnut has had a hard life.

It is growing out of a buried root, which may be as old as 150 to 200 years, the caretaker said.

“In the beginning, it would grow to a foot or two, then die back, no matter what I did,” said Hartz.

Over the past 20 years the tree “has grown slowly to its present height, and I have done my best to cultivate it,” he said.

“I’ve consulted experts such as Washington’s tree experts, Tom Osborne and Gary Lord, as to what steps were needed to help it survive.”