Marronnier Officiel de la Treille
Since 1818, Geneva has officially announced the arrival of spring on the day that a particular horse chestnut tree (the marronnier officiel de la Treille) first comes into leaf. The handwritten record of the marronnier officiel, kept in a glass safe box in the Grand Conseil, provides an unexpected indicator of local climate history. Although four different trees have been observed over the years since 1818, the clear general tendency for these trees to come into leaf earlier with passing years corroborates the warming trends established by climatologists. Linking nature and culture, an object of a public ritual becomes a telling document of the Anthropocene.
Images: The Marronnier Officiel de la Treille and documentation of its leafing. Photos by TAAG. Click on images to view enlarged and restored to original formatting.