Commentary Purg XXIII 34-36

For the fruit of the tree and the water flowing over its leaves that cause such appetite, see [Purg XXII 137-138]; and see the later reference in this canto ([Purg XXIII 62-63]).  That this desire is good but not yet realizable would seem again to point to the notion that this tree is descended from the Tree of Life.  See C.Purg.XXII.130-135.