Question: Who is Donatus, Landgrave Of Hesse's maternal grandmother?
Sentence (from "Donatus, Landgrave of Hesse"): Donatus, Prince and Landgrave of Hesse ("Heinrich Donatus Philipp Umberto"; born 17 October 1966) is the eldest son and successor of German aristocrat Moritz, Landgrave of Hesse, and his former wife, Princess Tatiana of Sayn-Wittgenstein-Berleburg.
Relevant evidence: Yes