The Callery pear tree, in nature is an invasive species. When grown as a bonsai it is an attractive species. They are a resiliant tree, as shown in a story below the photos about the "Survivor Tree" from September 11, 2001.
A Callery pear tree became known as the “Survivor Tree” after enduring the September 11, 2001 terror attacks at the World Trade Center. In October 2001, a severely damaged tree was discovered at Ground Zero, with snapped roots and burned and broken branches. The tree was removed from the rubble and placed in the care of the New York City Department of Parks and Recreation. After its recovery and rehabilitation, the tree was returned to the Memorial in 2010. New, smooth limbs extended from the gnarled stumps, creating a visible demarcation between the tree’s past and present. Today, the tree stands as a living reminder of resilience, survival, and rebirth.
Google "The Survivor Tree" for the full story and photos.