Gray Poplar

Warsaw's, on a pavement corner in Mokotow, was surveyed for its national register listing at 21 metres tall and 3.58 metres round, with nobody able to say whether it stood through the 1944 uprising. Sofia's is the oldest tree in the Doctors' Garden, planted in 1892, four years before the garden itself formally opened as one of the city's first botanical collections, and its survival as an ordinary wild-type poplar among later, showier imports is part of what earned it protection. Ferrara's, over 150 years old and 4.44 metres round, grew for most of that time screening a private courtyard at the Palazzo dei Diamanti, one of the Italian Renaissance's most recognisable buildings, until a 2023 restoration opened the garden to visitors. All three are protected by name: Poland's and Italy's national monumental-tree registers, and Sofia's own municipal listing.