משנה על נדרים 7:2

If he used one of these [baskets] as seed, he is exempt, and the second is treated as if it were terumah and subject to the law of hallah, the words of Rabbi Meir. But Rabbi Yose exempts it. If another person uses the second as seed, then he is exempt. If one man uses both as seed, if it is of a kind whose seed disintegrates [in the ground] it is permissible, but if it is of the kind whose seed does not disintegrate it is prohibited.

He who weeds allium plants (whose seeds do not disintegrate) for a Gentile, even though the produce is untithed he eat from them in a casual fashion. Saplings of terumah which had become unclean and were re-planted, become clean from their uncleanness. But they must not be eaten until the edible part [of the stalk] has been lopped off. Rabbi Judah says: he must [before eating] lop off a second time that which grew on the edible part.