(Mishnah): Kilayim of a vineyard may not be planted or allowed to remain and one may not gain benefit from them.

Kilayim of seeds may not be planted or allowed to remain but one may eat them and certainly one may gain benefit from them.

Kilayim in clothing (Shaatnez) are permitted in all ways except in wearing them.

Kilayim of animals may be bred and allowed to remain and it's only prohibited to mate them.

Kilayim of animals are prohibited to each other.

(Gemara): Kilayim of a vineyard may not be... etc. The pasuk states (Devarim 22:9), "You shall not sow your vineyard with Kilayim''. And the prohibition to allow it to remain is learned from the pasuk interrupting the phrase, "Don't sow - Kilayim'' with the words "your vineyard'' (which could have been written afterwards). This teaches that Kilayim are prohibited in your vineyard even without planting them, i.e. by allowing them to remain. Does this specifically follow R. Akiva who says that one transgresses a negative commandment (and incurs lashes) when he allows Kilayim to remain?

Answer (R. Yosa): This follows all opinions - all agree that it is prohibited (but the Chachamim hold that one would only receive lashes if he actually acted to allow the Kilayim to remain).

This is like the Baraisa that taught that one who covers seeds of Kilayim receives lashes (since an action was done to allow them to grow).

What is the source that one may not gain benefit from Kilayim? The pasuk here continues (Devarim 22:9), "lest it become prohibited'' and it says earlier about idols (Devarim 7:25), "lest you be ensnared ('Tivakesh') by it'' - just as with the 'lest' of 'lest you be ensnared' one may not gain benefit, so too here.

Source #2: It says here, "lest it become prohibited'' and it says further on (Devarim 23:18), "there shall not be a promiscuous man from amongst the children of Israel'' - which prohibits a man having relations with a slave woman or slave. Just as over there, it is prohibited to gain benefit, so too here.

Question: May one not gain benefit from a promiscuous man?

Answer (R. Chuna): Benefitting from relations with him is prohibited.

Source #3 (R. Chanina): The pasuk states "Pen Tikdash (lest it become prohibited)'' - which is expanded to be read as Pen Tukad B'Eish - lest it need to be burned. (This shows that if you grow or allow Kilayim to grow, it will become prohibited to gain benefit from it.)