(a) The Mishnah rules that a laborer ...
1. ... is permitted to eat from the branch of a fig-tree which protrudes into the garden, even though the trunk grows in the Chatzer.
2. ... is forbidden to eat from the branch of a fig-tree which protrudes into the Chatzer, even though the trunk grows in the garden.
3. ... Chutz la'Aretz, but whose trunk grows in Eretz Yisrael, or vice-versa - we always go after the trunk to determine whether the tree is subject to Ma'asros or not ...
(b) ... because the tree's Kedushah is determined by where it nurtures from.
(c) The Tana also rules that if the branch of a tree that grows over the wall of a walled city -- even though the tree is growing inside the city -- the branch follows the trunk, and the owner who sold it is permitted to redeem it only up to one year after the sale.
(a) When the Tana states that regarding Arei Miklat, everything goes after the branch, he means - that if the 'murderer' reaches the trunk of a tree which is outside the wall, the Go'el ha'Dam is not permitted to kill him, because the branch of the tree is inside (and he could certainly not kill him once he reached it).
(b) This does not mean that, in the reverse case, where the 'murderer' had reached the branch of the tree that was outside, the Go'el ha'Dam would be permitted to kill him, even though the trunk was inside - because, when the Tana says that we go after the branch, he means (not that we go after the branch exclusively, but) that we also go after the branch. But we certainly go after the trunk.
(c) Finally, the Tana says (in connection with Ma'aser Sheni) that if the branch of a tree that is growing inside Yerushalayim protrudes over the outer wall, or vice-versa - we go after the branch (which here too, means also after the branch).
(d) The ramifications of this ruling with regard to a tree that grows ...
1. ... outside, but whose branch is inside are - that just as, once he reaches the branch he is no longer permitted to redeem it, so too, when he reaches the trunk.
2. ... inside, but whose branch is outside are - that just as, once he reaches the branch, he is not permitted to eat it because he is still considered to be outside, so too, is he forbidden to eat by the trunk, even though he is already inside the walls.