(Mishnah): There were fruits about which the Chachamim were lenient and did not require separating Maaseros - Shitin (wild figs), Rimin (jujube fruit), sorb apples, wild white figs, young Sycamore figs, unripe dates, Gufnan (late grapes) and caper berries. In the region of Yehuda, they were also lenient about sumac (a type of cashew), vinegar and Kusbara (coriander).

(R. Yehuda): All wild figs are exempt, except for Diufra (that grows twice a year); all Rimin are exempt, except for Rimin of Shikmonah; all young Sycamore figs are exempt, except for Mustafos.

(Gemara) (R. Yochanan): The Chachamim gave this list since most of these species come from Hefker.

(R. Shimon ben Lakish): The Chachamim only taught Demai, but definite (untithed produce) is obligated.

(R. Yochanan): Whether Demai or definite, they are exempt.

Question (against R. Yochanan): But the Mishnah itself implies only Demai and not definite (when it is said 'the fruits for which the Chachamim were lenient', because they are Demai and not definite)...?

Answer (R. Ila): The 'lenient' cases of the Mishnah also include definite cases. Demai is mentioned because it is the subject of the entire Masechta.

A later Mishnah (Halacha 3 - Zevachim 81-2) supports R. Yochanan - 'From Kaziv (at the northern edge of Eretz Yisrael) and beyond is exempt from Demai'. Since Kaziv and beyond is not part of Eretz Yisrael, even definite (non-tithed produce) is also exempt from tithing; and the same is true of our Mishnah (that it also applies to definite).

Question (Tosefta Demai): (Against Reish Lakish) If these species (listed in our Mishnah, that are usually ownerless) were guarded (by the Am HaAretz owner) they are obligated (in Maaseros. This is assumed to mean that as long as the Am HaAretz owner guarded them, even if the rest of the world discards them, they are obligated). But since most of these fruits come from Hefker, the Am HaAretz will not refrain from tithing them, so why are they now obligated?

Answer: The Tosefta means that if most people of that area guard it, the Am HaAretz will refrain from tithing and the buyer is therefore obligated, whether it is Demai or definite. If most people do not guard it, all agree that it is exempt, whether it is Demai or definite.

Question: And if you say that perhaps the dispute (between R. Yochanan and Raish Lakish) is when exactly half the people guard it; it was already taught (in a Mishnah in Maseches Machshirin) that half and half is Demai...?

Answer (R. Zeira): The phrase 'half and half' is not speaking about the 'lenient' ones; it refers to regular 'important' produce (that is obligated in Terumos and Maaseros - therefore 'half and half' is obligated. Our Mishnah is discussing inferior fruit that can be assumed to be from Hefker, where it could be that R. Yochanan exempted even definite Tevel. Reish Lakish is lenient if they are Demai.)