On the outskirts of early Boston, not far from where livestock grazed on Boston Common, an impressive elm tree towered over the corner of Orange and Essex streets.
From its branches hung the effigies of British loyalists trying to enforce the Stamp Act. And when those taxes were repealed, flags and lanterns glowed from the same boughs.
The Liberty Tree, as it was known, gave root to the freedoms of speech and assembly in the years leading up to the American Revolution.
British soldiers and loyalists cut down the elm in spite in 1775, turning it into a powerful symbol of suppression and censorship. Only a stump remained.
Today, the Liberty Tree is remembered with a plaza by the Chinatown T station — roughly where the tree was rooted centuries ago. Its legacy of free speech in the country’s founding documents is easy to trace.
But a recent priority for the Massachusetts Historical Society was checking that the roots in their collection are actually from the Liberty Tree — from an American elm. When that stump was removed to make way for the expanding metropolis in the 1800s, a savvy Boston police detective named Derastus Clapp dug up a few pieces of the tree’s roots and donated them to the historical society.
Even more important, historians say, is preserving the ideas connected with them.
“You could say that it’s just a bunch of twigs,” said Kanisorn Wongsrichanalai, chief historian at the Massachusetts Historical Society. “But ... it has power because it’s what we believe it is, right? It’s what we endow it with: this mystical memory.”
A scientific inquiry unfolds
Those remains, skinny brown roots wrapped in faded red tape, were kept in a climate-controlled drawer for over 160 years until historians there decided to have the specimens tested.
“We realized that, well, no one had actually ever questioned whether they were from an American elm,” Wongsrichanalai said.
Just a few years ago, in 2023, they decided to check the most fundamental question: Were these roots truly from the same tree species?
Wongsrichanalai turned to Ned Friedman, the director of Harvard University’s Arnold Arboretum, first sending him a magnified image of the root ends.
“I had started out thinking ... first of all, it’s not an elm,” Friedman told GBH News.
He looked at how the roots transport nutrients and water and saw that they aren’t “ring porous.” Pores are the tree’s vascular system, functioning like a set of pipes throughout the plant. Elms and some other species are ring porous — their pipes forming distinct layers, or rings, with each growing season.
But the Liberty Tree sample looked different, Friedman said.
“You see pipe, pipe, pipe, pipe, pipe as you go from the middle to the outside,” he said. “That’s called ‘diffuse porous.’ And that’s not what elms are.”
Researchers who study wood anatomy spend most of their time on the chute system, which forms a tree’s trunk and branches.
But it occurred to Friedman: Root anatomy is less studied. So Friedman went back to the library. He found a study from nearly 40 years ago where German researchers had meticulously studied the anatomy of elm roots.
The researcher had cut roots at multiple sections starting from the base of the tree and traveling out. One cross section — measured at seven meters from the trunk — looked exactly like the little bundle at the Massachusetts Historical Society.
“I should never have assumed that what’s going on in the chute system would be mirrored in a root system,” Friedman said.
The Liberty Tree is not an ... English elm, right?
This meant it was highly likely the bundle of roots were indeed from an elm tree.
Yet there were at least two types of elm trees growing in Boston during that time: American elms, native to the landscape, and English elms, brought over and planted by colonists.
Could the Liberty Tree, a symbol of American patriotism, actually be an English elm?
“I always thought it’d be such a great irony if it did turn out to be an English elm,” laughed Brandon Scott, a recent MIT PhD graduate who wrote his dissertation on 19th-century American tree landscapes.
The Liberty Tree grew not far from Boston Common, which was bordered by English elms. Those elms were planted along the Common as the space was transitioning into more of a park, Scott said.
Scott believes the Liberty Tree was probably an American elm. City of Boston records from the 1600s report that the Liberty Tree was planted in 1646. Other records suggest it was growing there before the English arrived — which, Scott said, would definitively make it an American elm.
Friedman now says it’s “highly likely” that the historical society’s sample is indeed an American elm. For Wongsrichanalai, these results give the historical society “greater confidence” that the roots are what Detective Clapp said they were in 1860.
But the only way to really confirm that it’s an American elm is through DNA analysis. Friedman said he might do that one day.
