Bava Batra 82: Branches, Roots, and the Palm Tree's Smooth Trunk

When one owns trees in the middle of another's property, how is growth on the tree ascribed to either owner (new branches, new roots)? What if there's water and sediment and other debris covering the roots? Note: 3 trees together in another person's property is sufficient for the tree-owner to own the land their rooted in as well. Also, trees must be between 4 and 8 amot apart for these details to apply. Or was that between 8 and 16 amot? (it's a machloket) Noting that planting in the space between can be permitted or a violation of "mixtures" -- kilayim -- depending on how far apart the trees are.