(Mishnah): Wheat and Zunin (an inferior type of wheat) are not considered Kilayim with each other. Barley and oats, spelt and rye, Pul and Sapir, Purkadan and Tofach, Pul Halavan and She'u'it are not considered Kilayim with each other.

(Gemara): The pasuk states (Vayikra 19:19), "You shall not plant Kilayim in your field". I would think that this applies even to two types of wheat or two types of barley.

The pasuk said previously, "You shall not crossbreed you animals". I would think that this applies even to a black ox with a white ox.

The pasuk ends by saying, "A mixed garment of Shaatnez should not come upon you". I would think that this even applies to two types of wool together or two types of linen together. But another pasuk explained (Devarim 22:11), "You shall not wear Shaatnez, wool and linen together". If so, just as for Kilayim in clothing, I only prohibited two completely different species together, so too in all types of Kilayim, I only prohibited two completely different species together (but not two types of the same species).

The Mishnah taught that wheat and Zunin are not Kilayim - but Zunin with barley would be Kilayim.

Question: 'Wheat and Zunin are not Kilayim.' Zunin are not fit for human consumption, so why would I think that planting it with wheat would be Kilayim? (This Gemara is a source that seeds that are not food do not have a prohibition of Kilayim.)

(R. Ba bar Zavda): Some places keep them to feed to doves (so they are considered food).

Question: Is R. Ba bar Zavda coming to explain the Mishnah like R. Eliezer? As the Mishnah taught (in the 5th Perek), 'If one allows thorns to grow in a vineyard, R. Eliezer says that it becomes prohibited (because of Kilayim) and the Chachamim say that it does not...?

(R. Abahu): R. Eliezer reasons that there are places in Arabia where they allow such thorns to grow for feeding their camels.

Question: What do the Rabbanan reason? That there aren't places in Arabia where they allow it to grow? Let them investigate it!

(Rabbanan): In a place that they allow it to grow, it is prohibited; but in a place that they don't, it is permitted.

What's R. Eliezer's reasoning? Once they allow it to grow in one place, it becomes prohibited everywhere.

Conclusion of question: So isn't R. Ba bar Zavda following the view of R. Eliezer?

Answer: There, it's not normal to bring thorns from place to place (so the Rabbanan disagree and say that it is only prohibited in a place where it is actually given to camels.) Here, it is normal to bring Zunin from place to place (so it is considered to be eaten everywhere).

Question: If it's moved from place to place, Zunin should be considered Kilayim with wheat?

Answer (R. Yona): They are a type of wheat, but when the wheat is spoiled, it grows as Zunin; as the Baraisa taught - the pasuk states (Vayikra 19:29), "...that the Land not fall into harlotry (Tizneh)" - from here we learn that the produce grows abnormally.