Kilayim, Chapter Two, Mishnah Two
Todays mishnah is a direct continuation of yesterdays mishnah. In sections two and three it brings up some exceptions to the general rule that 1/24 of a different seed(s) will forbid a mixture.
1) To what does this refer? To [an mixture of] grain [occurring] with [different] grain, or pulse with [different] pulse, to grain with pulse, and to pulse with grain.
2) However they stated: Seeds from a garden which are not eaten, they add up [with other seeds to form an amount sufficient to prohibit the sowing of a seah] when there is 1/24 of the quantity [of such seed] that is necessary to sow a bet seah.
3) Rabbi Shimon says: just as they ruled to be stringent so too they ruled to be lenientflax [mixed in with] produce, combines when there is 1/24 of the quantity [of such seed] that is necessary to sow a bet seah.
Section one: The rule in yesterdays mishnah only applies to a case where grains and pulse (beans) became mixed up. In section two we will see that the rule for garden seeds is different.
Section two: However they stated implies that there is a rule in this section that deviates from the normal rule above. The mishnah refers here to inedible seeds such as garlic seeds or turnip seeds. If there is in a mixture 1/24 of these seeds in the amount of seeds of grain needed to plant a bet seah (a plot of land that can grow a seah of produce, about 2500 square cubits), but in this size field the seeds would produce much less than a seah, such as a kav, then 1/24 of a kav of these seeds would prohibit a mixture of another seah of other produce (remember grain prohibits if there is 1/6 of a kav). In other words, since these seeds, if they were grain seeds, would produce a much smaller amount of product if they were planted in a field that could grow a seah of produce, they prohibit mixtures at 1/24 of the level of the amount of product that they would produce, in this case 1/24 of a kav.
Section three: In the previous section we saw a stringency with regard to garden seeds that are not eaten. Since these seeds produce much less product, the laws are more stringent in their prohibiting a mixture with other produce, such as grain. In contrast, when an equal amount of flax seed is planted in a plot of land used to produce a seah of grain, it will produce three seahs of flax (three times the amount of grain). Therefore, the law is more lenient with them and there will need to be ¾ of a kav of flax seeds mixed in with other seeds before they become prohibited.
As a general rule we could summarize that if an amount of seed produces less final product, it will be more potent in prohibiting mixtures, but if it produces more final product, it will be less potent in prohibiting mixtures.