What is the oldest tree in Berlin?

Two credible sources disagree on Dicke Marie's age by several centuries, which is unusual even for a tree this old: Berlin's forestry office has long cited 800 to 900 years, while the German Dendrological Society's own National Heritage Tree board reassessed it in 2021 and concluded 500 to 600 was more defensible, since internal decay makes precise dating impossible either way. This page states both rather than picking the more dramatic number. What is not disputed is the tree's identity: two Humboldt brothers, Alexander and Wilhelm, are said to have named it after their family cook around 1800, while summering nearby at Schloss Tegel, and the nickname stuck for over two centuries. On 9 July 2021 Dicke Marie became the first forest tree in Germany named a National Heritage Tree. It stands in the Tegel Forest on the northeastern tip of Tegeler See, reached on foot from the Alt-Tegel U-Bahn station via the harbour bridge and lakeside path. A short walk further into Schlosspark Tegel stands the Humboldteiche, a younger but far thicker oak that is sometimes confused for the record holder; the two are neighbours, not the same tree.