An esrog is equal to a tree in three ways and to vegetables in one way. It is equal to a tree for orlah, for reva'i and for the seventh year. And [it is equal] to vegetables in one way, that at the time of its picking [is] its year of tithing. [These are] the words of Rabban Gamliel. R' Eliezer says: [It is] equal to a tree for everything.