‘Inestimable Importance’: 500-Year-Old Cache of Pressed Flowers Reveals New Secrets

Thousands of specimens from the 1500s show huge changes to Bologna’s flora due to climate crisis and migration, say researchers

A collection of pressed flowers taken from the hillsides of Bologna 500 years ago is unlocking knowledge about how the climate crisis and human migration is changing landscapes in northern Italy.

Picked between 1551 and 1586 by the Renaissance naturalist Ulisse Aldrovandi, the 5,000 delicately cut and dried plants form one of the richest collections of its time.

Aldrovandi’s original purpose was to identify plant species and understand which could be used for pharmaceutical purposes. Nearly half a millennium later, his carefully pressed specimens are helping botanists document the enormous changes that have taken place in the surrounding landscapes, according to new research published by the Royal Society.

During Aldrovandi’s time, Bologna’s hills were rich in species that are threatened or have even disappeared today, such as motherwort, which was used for medicinal purposes and is now likely extinct in the region. The total number of the species has increased since 1500s, but the quality of the flora has decreased, with many rarer species declining, researchers said. The Italian population increased by 560% during the study period.