Sacred plant impressions from Somma-Vesuvius volcanic ash deposits: A medicinal garden in Late Antique Acerra (Naples, Campania, Italy)?

The AD 472 eruption of Somma-Vesuvius widely impacted the northern and eastern territory around the volcano, laying down a complex sequence of pyroclastic fallout and pyroclastic current deposits. During archaeological test excavations conducted in the Acerra locality, Pollena eruption (AD 472) fallout and lahar deposits composed of fine ash containing traces of plant impressions were found. These deposits were sampled and carefully fractured in order to recover the plant imprints. Features of the ash impressions were compared with those of live plants and dried Herbarium specimens. Species identification was based on the characteristics of leaves (maximum width, type of leaf margin, size of midrib, angle of formation of the secondary veins) and fruits. Impressions of Mandragora officinarum L., Rosa canina L. and Hedera helix L. were recognized. This is the first documented discovery of subfossil mandrake specimens. The use of mandrake plants for healing and psychotropic purposes is referred to by Classical authors such as Pliny the Elder and Dioscorides; it was sometimes used mixed with rose. In addition, rose and ivy plants were symbolically important to the ancient Romans and were employed together as medicinal plants. The coexistence of these plants in a restricted area suggests the presence of a garden dedicated to sacred/medicinal plants. In addition, it is interesting to note that the discovery of mandrake plants with fruits supports the hypothesis that the eruptive event took place between the end of summer and the autumn.