Md. Code, Real Property § 8-107

If there is no demand or payment for more than 20 consecutive years of any specific rent reserved out of a particular property or any part of a particular property under any form of lease, the rent conclusively is presumed to be extinguished and the landlord may not set up any claim for the rent or to the reversion in the property out of which it issued. The landlord also may not institute any suit, action, or proceeding to recover the rent or the property. However, if the landlord is under any legal disability when the period of 20 years of nondemand or nonpayment expires, the landlord has two years after the removal of the disability within which to assert the landlord’s rights.