Iowa Code § 614.36: Lessors, reversioners, and easements.

This chapter shall not be applied to bar any lessor or lessor’s successor as a reversioner of the lessor’s right to possession on the expiration of any lease; or to bar or extinguish any easement or interest in the nature of an easement, the existence of which is apparent from or can be proved by physical evidence of its use; or to bar any right, title or interest of the United States, by reason of failure to file the notice herein required.