The zoo is branching out.
The Bronx Zoo introduced a “functionally extinct” tree species at its grounds Monday — more than a century after the institution’s own scientist discovered a deadly fungus was decimating the plants.
Twenty American Chestnut saplings were scattered across three sites at the sprawling conservation center, including at the footsteps of Tiger Mountain, as part of a city-wide effort to breathe life back into the species.
“It’s historic for us. We haven’t had chestnuts on property here for a hundred years,” Craig Piper, the interim director of the Bronx Zoo, told The Post as he watched his team tenderly plant the tiny trees…