Bikkurim 2:6-7

Bikkurim 2:6

An esrog tree is like other trees in three ways: regarding the laws of orlah, revai (fourth-year produce) and the sabbatical. An esrog tree is like vegatables in one way: it becomes obligated in tithes at the time when its produce is gathered. This is the opinion of Rabban Gamliel; Rabbi Eliezer says that an esrog tree is like other trees in all ways.

Bikkurim 2:7

Human blood is like animal blood in that it can render produce susceptible to ritual impurity. It is like the blood of sheratzim (creeping things) in that a person does not receive a court-imposed penalty for eating it.