Next year, visitors at the new 9/11 memorial will understand why.
The tree, its trunk scorched and branches stripped, was rescued from Ground Zero after the terrorist attacks, and Cabo has spent nine years tenderly nurturing it into a symbol of rebirth.
"I love this tree," said Cabo, 54, a Parks Department employee.
Originally planted in an outdoor concourse at the Trade Center, this remnant of 9/11 will be replanted next year at the National September 11 Memorial & Museum.
"For me, it's going to be emotional," Cabo said, anticipating the day when the "survivor tree" is removed from the Arthur Ross Nursery in Van Cortlandt Park.
"But I am going to be happy that she is going back to where she came from."
When the memorial opens on Sept. 11, 2011, the hardy callery pear tree will anchor a glade of trees near the memorial's heart - two 30-foot waterfalls covering the original footprints of the twin towers.
The burning debris from the falling skyscrapers reduced the then-8-foot-tall tree to a limbless, charred trunk, coated in ash.
"It had one branch that had one tiny little shoot coming out of it, with a leaf on it," Clough said. "It was like the only glimmer of hope there was."
When the tree was first hauled to the Arthur Ross Nursery and planted on Veterans Day2001, Cabo thought the prognosis was grim.
But he and retired Parks Department worker Robert Zappala, 58, of Queens, went to work on their new patient. The tree was replanted in the park's rich soil, and its dead limbs and tissue were clipped to allow it to heal.
Fertilized regularly, it perked up almost immediately. It has been carefully trimmed over the years, to help its natural shape return. Scars are still visible where its limbs were blown off, but it has grown to about 35 feet - and become a source of wonder.
"Everybody that looks at the tree looks at it in awe," Cabo said.
The scars give it special resonance for the many first responders sickened during long hours amid Ground Zero's toxic dust, Zappala said.
"It represents a survivor, a seriously injured survivor of the World Trade Center," Zappala said. "It's something they can look at in the world of survivors."
The tree was uprooted in the vicious March nor'easter that downed hundreds of trees citywide.
Since replanted and restored, it's doing fine, said Cabo, who thinks the storm only added to the parallel between the tree and the post-9/11 city it represents.
"I think of the way the city bounced back and the way the tree keeps bouncing back," Cabo said. "It's a New Yorker."
The Hudson is measured north from Hudson River Mile 0 at the Battery at the southern tip of Manhattan. The George Washington Bridge is at HRM 12, the Tappan Zee 28, Bear Mountain 47, Beacon-Newburgh 62, Mid-Hudson 75, Kingston-Rhinecliff 95, Rip Van Winkle 114, and the Federal Dam at Troy, the head of tidewater, at 153. Entries from points east and west in the watershed reference the corresponding river mile on the mainstem.