The Grey Walnut of the Botanical Garden

Bologna's grey walnut is the only Juglans cinerea recorded anywhere on Italy's national register of monumental trees, one specimen among more than 4,500 entries. It grows in the university's botanical garden on Via Irnerio, close to the ginkgo at the garden's front section, and stands 32 metres tall, a serious height for a species native to the river valleys of the eastern United States and Canada rather than to Italy. The regional register measures its girth at 4.2 metres; university-cited press coverage of a 2025 conservation project puts it nearer 4.7, and neither figure has been reconciled here, so both are recorded rather than one invented winner. That conservation project is the tree's real story right now. Professor Alberto Minelli of the university's agro-food science department began a five-year programme in February 2025 to monitor a specimen the garden's own curator, Umberto Mossetti, describes as living in an extremely delicate balance with what surrounds it: reached what the university calls an irreversible aging phase, vulnerable to parasites and disease, and under added pressure from a changing climate. Nobody has recorded when it was planted. What is on record is that the university is treating its survival as a live question rather than a settled fact, five years of advanced diagnostics and soil analysis aimed at keeping the only tree of its kind on Italy's whole register standing a while longer.