(Mishnah): The following things divide for Peah (to require the field on either side of it to have Peah given separately) - a river, a (main) canal, a private road, a public road, a private path, a public path that is (constantly) used both in the summer and in the winter, an uncultivated land, a plowed land, a row of another species.

Produce that did not reach a third of its growth that is cut as animal fodder and resting on the ground - R. Meir says that it separates and the Chachamim say that it only separates if he plowed there.

(Gemara) (Baraisa): The pasuk says (Vayikra 19:9), "your field" (in the singular) - this teaches that one must give Peah from each field separately, but not from one field for another. (Note: The explanations of the sugya in the entries that follow are according to Rav Chaim Kanievski.)

However, this teaching is not definitive, as it is in fact only a Rabbinic law (and the pasuk is merely used as an allusion to it); as if it would be a Torah law, the divisions listed in the Mishnah should even apply to an orchard;

As the Mishnah teaches (further on, daf 20 - Perek 2 Halachah 3), "Everything divides for seeds but only a fence divides for a tree" - doesn't this show that a fence is a definite (Torah) division?

No, even a fence is Rabbinic - if you say that a fence being a division is a Torah law, it should divide even if the branches are interlocked and reaching over the fence; but it is taught (in that same Mishnah) that it does not divide in that case, which shows that it is not a Torah law.

One might ask that since a fence is a Torah division, it should divide even there are interlocking branches over it; this is not a question - since once could say that the Torah disqualifies a fence that has such branches over it. If so, one would think that even when the branches interlock on only one side of the fence it should also disqualify the fence; but this is not the case, as the Baraisa taught that if there are interlocking branches on both sides, it does not divide; meaning that if only on one side, it divides. (Note: This entry follows the explanation of the Birkas Kohen)

(R. Yosi citing R. Yosi b'R. Chanina): If one separated Peah from one field for another, it is not valid.

Question (R. Zeira to R. Yosa): If there was a Meitzar (a narrow strip of land at the border between two fields which is often either higher of lower than the fields on each side) and he gave Peah from it for the fields on either side, is it valid? R. Yosa avoided answering R. Zeira (as the answer was not clear to him).

Question: The view of R. Yosa seems to have changed, as the Mishnah (later on Perek 3 Mishnah 2) teaches - the Chachamim agree with R. Akiva that if one sows his field with dill or mustard in three different places, Peah is given from each patch separately - the Mishnah is referring to dill in three places or mustard in three places.

Conclusion of question: Shmuel explained that since the patches do not ripen at the same time, they are each considered as separate fields. But R. Yasa explained from R. Yochanan that it is because it's normal to sow in patches (and each patch is considered a separate field). If so, why was R. Yosa doubtful about this when R. Zeira asked him about it (above (f))?

Answer: He was certain that ideally, one may not give Peah for the fields from the Meitzar; but he was doubtful about when a person nevertheless did so, whether or not it is valid Peah (Bediavad).