Before us is Mishnah 10, the last in chapter 3. Following the previous mishnah's discussion of fig trees growing in courtyards, we will deal here with a tree that stands in a courtyard while its branches extend outside it, and from there we will broaden the scope to all cases in which a single tree stands between two halachic domains.
The opening question is this: a fig tree whose trunk grows in a courtyard while its branches lean out beyond the courtyard, and a person stands outside and eats there - does the obligation of maaser apply? The mishnah answers that it does not. This is novel, since ordinarily the status of a tree is determined by the place where its trunk emerges from the ground. The explanation is simple: the obligation of maaser does not depend on where the tree stands or on its status, but on whether the processing of the fruit has been completed and the fruit has been brought into the house. Fruit that is outside the courtyard is not considered to have been brought into the house, and therefore it is exempt when a person eats it outside.
The mishnah then examines additional cases in which the trunk grows in one halachic domain while the branch crosses the line into another. The guiding rule is that the status of a tree follows its trunk and not its branches, but in several scenarios - where the status of the tree itself is not the issue under discussion - it is precisely the location of the branch that is taken into account.
"Te'einah shehi omedes bechatzer venotah laginah":
A fig tree stands inside a courtyard of the type that obligates the separation of maaseros, and its branches lean over the courtyard wall into the garden, and a person stands in the garden and eats from the branch that is outside - "ochel kedarko patur" - he eats in his usual manner and is exempt. Even if he eats in the normal way, that is, taking two figs or more at once, he is not obligated. Had he been standing in the courtyard, this would constitute a combining that obligates the separation of maaser by rabbinic law, but since he is located outside the courtyard, this is an incidental eating and the fruit is exempt from maaseros.
"Omedes baginah venotah lechatzer":
In the reverse case, the fig tree stands in the garden outside the courtyard and its branch leans and droops into the courtyard, and the person stands inside the courtyard and picks from the branch. Here, since he is standing in the courtyard, he may eat only one fig at a time, and in this manner he is exempt from maaseros. But if he gathered two figs or more, or, in the words of Rabbi Shimon, one in each hand and one in his mouth, this is a combining, and he must separate maaseros by rabbinic law before eating.
It emerges that the determining factor in both cases is where the person is standing, and not the location of the tree or of the branch in itself.
Eretz Yisrael and outside the Land:
From here the mishnah moves to the question of the status of the tree itself: is it obligated in maaseros? In Eretz Yisrael the answer is yes, and outside the Land there is no obligation, at least not by Torah law. What is the law regarding a tree whose trunk is in Eretz Yisrael and whose branch crosses the border to outside the Land, or the reverse, its trunk outside the Land and its branch leaning into the airspace of Eretz Yisrael? In both cases everything follows the trunk of the tree, that is, the place from which it emerges from the ground. This is the tree's primary part, from which it draws its nourishment, and from it its halachic status is derived. A tree growing in Eretz Yisrael is obligated in maaseros regardless of where its branches spread, and a tree whose trunk is outside the Land is exempt even if its branches are within Eretz Yisrael.
Houses in walled cities:
The next question concerns the status of houses in walled cities. An introduction is needed: Eretz Yisrael was divided among the twelve tribes, and the underlying idea is that ancestral portions should remain the permanent possession of the tribe and the family that inherited them. Therefore, one who sells a field has the land return to its owner in the Yovel year that follows seven shemitah cycles. During the first two years the land cannot be redeemed, and after that the owner may redeem it back even before Yovel.
However, the Torah draws a distinction between Eretz Yisrael as a whole and cities surrounded by a wall. In such cities a different law applies, and they are exempt from the rule that ancestral holdings always return to their original owners: one who sells his ancestral home located inside a walled city has twelve months in which to redeem it and take it back, and once those twelve months have passed the house is lost to him permanently and does not return to him even at the Yovel.
The Mishnah asks: a tree whose trunk stands inside a walled city while its branches extend outside it, or the reverse - which laws apply to it? Is it property that returns at the Yovel, or property that must be redeemed within a year, after which it is lost? On this it says: "U'v'batei arei chomah - hakol holech achar ha'ikar" - and regarding houses in walled cities, everything follows the main part, that is, everything follows the trunk. Trees whose trunk stands within the city walls are sold permanently even if their branches extend outside the city; and trees whose trunk stands outside the city are not sold permanently even if their branches reach into it - they may be sold, and after two years they may be redeemed, and when the Yovel arrives the tree returns to the family of its original owners.
Cities of refuge:
The next case is the status of the cities of refuge. In brief: one who kills unintentionally under certain conditions may be avenged by the go'el hadam, the relative of the victim, who is permitted to kill him. The unintentional killer must therefore flee to one of the cities of refuge, of which there are forty two, and while he is there he is protected and the go'el hadam may not harm him. The protected area includes the city of refuge itself together with the two thousand amos surrounding it.
The Mishnah asks: consider a tree standing on the two thousand amah boundary line, whose trunk is within the boundary while its branches extend beyond it, and the unintentional killer is sitting on one of those branches. Measured through the air he is beyond the two thousand amos, yet the tree itself stands within the boundary. Does he receive the protection of the city of refuge?
The Mishnah says that regarding cities of refuge "hakol holech achar hanof" - everything follows the foliage, that is, the branch. The Bartenura explains that this is stated as a stringency: although the usual rule is that everything follows the trunk, when a person is sitting on the branch we apply the stringencies according to the location of the branch as well. In the case of the go'el hadam, the stringency is the restriction on killing. It emerges that one sitting on a branch that is more than two thousand amos from the city of refuge, while the trunk of that tree stands within the two thousand amos, receives the protection of the city of refuge, and the go'el hadam may not harm him, since we follow the foliage as well in order to protect him.
Yerushalayim and maaser sheni:
Finally the Mishnah deals with Yerushalayim, and in our case the subject is the laws of maaser sheni. The obligation of maaser sheni is to bring it to Yerushalayim and eat it there, and from this follow two laws:
Outside Yerushalayim: maaser sheni may not be eaten, but it may be redeemed - transferring the sanctity of the maaser from the produce onto a coin, bringing the coins to Yerushalayim and buying food with them.
Inside Yerushalayim: maaser sheni may be eaten, but it may not be redeemed. Maaser sheni food that has entered Yerushalayim may no longer leave it, and it may not be redeemed and taken out, but must be eaten there.
What is the law regarding a tree whose trunk is inside Yerushalayim while its branch extends over the walls to the outside, or the reverse - planted outside the walls with its branches reaching into Yerushalayim? Here, as with the cities of refuge, although the usual rule is that we follow the trunk, the question is not the status of the tree itself but rather whether the person is located in Yerushalayim, and therefore we follow the foliage as well, as a stringency.
It emerges that one sitting on a branch that crosses the line - whether he is sitting in the airspace of Yerushalayim on a tree whose trunk is outside, or sitting on a branch outside Yerushalayim while the tree is planted inside - is subject to the stringencies of both sides: he may not eat the maaser sheni, since perhaps he is not in Yerushalayim, and he also may not redeem the produce, since perhaps he is in Yerushalayim. We rule stringently in both directions.
In summary: in this Mishnah we learned that in matters of maasros the determining factor is where the person eating is standing, in the courtyard or in the garden; that regarding the status of the tree itself, in Eretz Yisrael and outside the Land and in houses of walled cities, "hakol holech achar ha'ikar" - everything follows the trunk; whereas regarding cities of refuge and Yerushalayim, where the question is where the person is located, we follow the foliage as well - the branch - as a stringency. With this, chapter three is complete.