[If] an olive tree is found standing between three rows of two squares, and he forgot it, it is not shich'chah.  [If] an olive tree has on it two seahs and he forgot it, it is not subject to the law of shich'chah. When is this said? If he has not started [to harvest] it. But if he has started [to harvest] it —- even if it is like the dripping olive in its time —- and he forgot it, it is subject to the law of shich'chah.  As long as he has underneath it, he has at its top. R' Meir says: From when the exposer goes through [it].