For the source text click/tap here: Nedarim 57
To download, click/tap here: PDF
The Gemara attempts to prove that the Gidulin are not like the Ikar and are permitted, and that they can annul the Ikar. The Gemara quotes the statement of Rebbi Yitzchak in the name of Rebbi Yochanan who says that when a person separated Terumos and Ma'aseros from onions and then replanted the onions in the ground and they increased in size such that there is more new growth of onion than the original growth of onion, he is obligated to separate Ma'aser not only from the new part that grows but from the entire onion, including the original growth. This ruling clearly indicates that any new growth which sprouts forth from an object which is exempt from Terumos and Ma'aseros is obligated in Terumos and Ma'aseros (that is, the Gidulin are not like the Ikar), and that they can annul the Ikar and cause the Ikar to become obligated in Ma'aser as well.
We explore the history biological properties and dubious health benefits of onions as well as the curious statement (Nidah 17) by Rabbi Shimon Bar Yochai that one who eats a peeled onion, egg or garlic that has been left sitting out overnight is literally endangering his life and will be ultimately judged as a person who took his own life.