The American chestnut, once abundant in the Appalachian Mountains, is now considered an endangered plant species due to disease.

The American chestnut tree was once a dominant species in the Appalachian Mountains but faced near-extinction in the early 20th century due to the spread of the chestnut blight, a fungal disease. This devastated the population of the tree, which was highly valued for its wood and edible nuts. Efforts to restore the American chestnut through breeding programs and genetic research are ongoing, with the goal of reintroducing a blight-resistant version of the tree to the Appalachian ecosystem.