The following post was contributed by Charlottesville friend Alan Mawyer.
And now for something amazing. I’ve seen trees (especially fruit trees) sprout from stumps but never a maple tree from the center of a stump. The only living part of the tree is the thin layer under the bark and the leaves, not the center. A graft would have to connect to the bark so that the periderms* merge. If a seed was planted in the middle of the tree, I would think it would have split the trunk.
*The corky outer layer of a plant stem formed in secondary thickening or as a response to injury or infection.