|The American Chestnut is a large, deciduous tree of the oak family native to eastern North America. Before the species was devastated by the chestnut blight, a fungal disease, it was one of the most important forest trees throughout its range. There are now few if any mature specimens of the tree, except where it was planted in blight-free regions distant from its original range. Once an important hardwood timber tree, the American Chestnut is highly susceptible to chestnut blight, caused by an Asian bark fungus (Cryphonectria parasitica, formerly Endothia parasitica) accidentally introduced into North America on imported Asiatic chestnut trees. The disease was first noticed on American Chestnut trees in the Bronx Zoo in 1904. While Chinese Chestnuts evolved with the blight and developed a strong resistance, the airborne bark fungus spread 50 miles a year and in a few decades girdled and killed up to three billion American Chestnut trees.