 New shoots often sprout from the roots when the main stem dies, so the species has not yet become extinct.However, the stump sprouts rarely reach more than in height before blight infection returns, which therefore, is classified as functionally extinct since the Chestnut Blight only actively kills the above ground portion of the American Chestnut tree, leaving behind the below ground components such as the root systems.It was recorded in the 1900s that the chestnut blight would commonly reinfect any novel stems that grew from the stumps of the American Chestnut tree and therefore maintained a cycle that would prevent the American Chestnut tree from re-establishing.