(Mishnah): One may not graft a tree onto a tree or a vegetable onto a vegetable, or a tree onto a vegetable, or a vegetable onto a tree. R. Yehuda permits grafting a vegetable onto a tree (and vice-versa).

(Gemara) Question: The opinion of R. Yehuda seems to have switched - there (earlier in Halacha 2) he said that a person sometimes plants a seed from the inner chamber of the Avatiach and a seed from the inner chamber of an apple and puts them in a pit and they combine and become Kilayim. But here, he said that there is no prohibition of Kilayim...?

Answer: There, by putting them together, they combine and become Kiyalim; here, they do not combine.

(Baraisa) Question: Where is it taught that one may not graft a non-fruit bearing tree with a fruit bearing tree or vice-versa - meaning that one may not graft one species with another...?

Answer: The pasuk states (Vayikra 19:19), "You shall keep My statutes: (You shall not crossbreed your animals with different species. You shall not sow your field with Kilayim (a mixture of seeds)"...

(R. Yona/ R. Eliezer citing Kahana): This Baraisa follows the view of R. Eliezer (who taught in the Sifra that 'you shall keep My statutes' - statutes that I engraved (Chukim SheChakakti) for Adam at the time of creation, that each species should remain unto itself - applies to all of the things listed in the pasuk - including mixtures of seeds - and it applies to all descendants of Adam - even gentiles).

(R. Yosi citing R. Hila): The Baraisa follows all opinions - even the Chachamim, who do not apply the prohibition of Kilayim to gentiles, agree that there is a prohibition of Kilayim because one is contradicting the rules established in the world (by its Creator).

Question: If so, it should be forbidden to graft a black fig tree onto a white fig tree?

Answer (R. Avin): Didn't you learn it from Kilayim of garments, where the prohibition is only to mix two completely different species; so too, only two separate species are forbidden (but not different types of figs).

Baraisa (citing R. Elazar): It's permitted for a gentile to plant and wear Kilayim, but not to crossbreed animals and not to cross-graft trees, as about those mixtures, the Torah said "Le'Minaihem".

Question: The word 'Le'Minaihen' is also used for vegetation (where there is no prohibition to graft vegetation together)?

Answer: The word 'Le'Minaihem' is not a command there but rather a description of their growth.

Question: If so, why was the land cursed (when man and the snake were cursed, if it didn't contradict a command that it was given)?

Answer (R. Yudan bar Shalom): As it transgressed the decrees of Hash-m - the pasuk says (Bereishis 1:11), "The land should produce vegetation, seed yielding herbs (and fruit trees producing fruit according to its kind)" (that the tree itself should be edible) and it actually did as the next pasuk describes, "And the land produced vegetation, seed yielding herbs according to its kind (and trees producing fruit)".

(R. Pinchas): The land rejoiced at Hash-m's decree and it added even non-fruit bearing trees.

Question: According to R. Yudan bar Shalom, that the land transgressed the decree of Hash-m, it is understandable that it was cursed. But according to R. Pinchas, why was it cursed?

Answer: It's like a person who becomes angry at his friend and says, "Cursed are the breasts that nursed him".

This follows the view of R. Noson, who said that three were judged (for transgressing the word of Hash-m - Adam, Chava and the snake), but four came out cursed.

Question: The pasuk only mentioned the prohibition of crossbreeding animals. What's the source that it applies to birds?

Answer: Some learn it from the earlier pasuk (Vayikra 19:19), "You shall keep My statutes; some learn the meaning of "You shall not crossbreed your animals" from the pasuk about resting from work on Shabbos (Devarim 5:13) that also includes beasts and birds.

The practical difference between learning from these two sources is if a person crossbreeded animals and birds in the same act - according to the first source, he is liable to two sets of lashes; according to the second source, he is liable only once.

If a person grafted a tree and crossbreeded birds in the same act, according to the first source he is liable once; according to the second source, he is liable twice.