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Answer It is the Callery pear, which was discovered burnt and buried beneath rubble at the World Trade Center 25 years ago. but is now flowering again. It is known as the Survivor Tree and was replanted on the site nine years ago. See more here.

If you guessed the tree of heaven, you were thinking outside the square! The tree of heaven is the tree that features in the 1940s novel, A Tree Grows in Brooklyn, by Betty Smith. It is considered a weed in Australia.