One who buys two trees in the field of another has not acquired any land. R' Meir says: He has acquired land. [If] they grew, he may not trim [them]. Whatever grows from the trunk belongs to him; from the roots, to the owner of the land; and if they died the land is not his.  [If] he bought three, he has acquired land. [If] they grew, he may trim [them]; whatever grows from the trunk and the roots belongs to him, and if they died the land is his.