Missouri Revised Statutes Title XXXV. Civil Procedure and Limitations § 516.080. When legal title has not emanated from the United States

In all cases in which the legal title has not yet emanated from the government of the United States, but in which there has been an equitable right or title for more than twenty years, under which a claimant has had a right of action by the statutes of this state, and in which the land has been in the possession of any person for twenty years, claiming the same in fee, any person claiming against the possessor shall bring his action under the legal title within one year after it issues from the government, and in default thereof, he shall be forever barred, and his right and title shall, ipso facto, vest in such possessor.