Macroremains of citrus fruit in Italy

The difficult preservation of Citrus carpological remains is probably the main reason why the presence of this genus was not documented in Italy until a few years ago. Indeed, the fleshy nature of its hesperidium does not facilitate good preservation, which has occurred in only a few sealed archaeological contexts: in anaerobic (poorly oxygenated) waterlogged environments (Rome), in extremely dry conditions (Egypt), after charring (Pompeii) or inclusion in mineral matter (Pompeii). In general, Citrus seeds from archaeological contexts are easily fragmented and for this reason they are sometimes unidentifiable. Additionally, the preservation processes may obliterate the diagnostic characters of cell patterns (shape, size and organization) and the seed’s keels. Another difficulty in identifying Citrus seeds to species level lies in their morphological variability. Sometimes, even the determination of fossil remains to genus level is difficult, as Citrus seeds may be confused with other taxa, for example Maloideae.5 The comparison of fossil Citrus seeds with modern reference samples is complicated by a long history of anthropogenic activity: selecting and crossbreeding to obtain different cultivars of the same species. Only after the publication of the paper by Pagnoux et al. (2013) were a number of morphobiometrical criteria established, with the aim of distinguishing C. medica from C. limon in the archaeobotanical records; quantitative techniques for analysing the shape of the seeds (modern and archaeological) were employed to shed new light on the complex history of the genus. These criteria have allowed the identification of Citrus seeds from recent excavations in Italy (Pompeii and Rome), and from various archaeological contexts, both before and during the Roman period. These data confirm the important role of the Italian Peninsula in the diffusion of Citrus throughout the Mediterranean Basin in ancient times.