Oktzim, Chapter One, Mishnah One
1) That which serves as a handle but does not protect, both contracts uncleanness and conveys uncleanness; but it is not included.
2) If it protects but is not a handle, it contracts and conveys uncleanness and is included.
3) If it neither protects nor serves as a handle, it neither contracts nor conveys uncleanness.
Section one: If the stem of a piece of produce serves as a handle by which to hold the produce, but it doesn’t protect the produce from spoiling, then it is considered part of the produce for issues of impurity. If the stem is defiled so is the produce and vice versa, if the produce is defiled so is the stem.
However, when determining the size of the piece of produce, this stem doesn’t count. So if the produce is less than the size of an egg, it cannot be defiled (see Toharot 2:1).
Section two: If it protects the produce even if it doesn’t serve as a stem, then it counts as part of it for all matters, even to be including in reckoning its size.
Section three: If it neither serves as a handle nor protects the produce, then it is not part of it for any issue of impurity.