Adding ‘flavour’ to past cuisines: First steps towards a phytolith reference collection of modern Mediterranean herbs

Most aromatic herbs belong to plants within the onion subfamily (Allioideae Herb.), the mint family (Lamiaceae Martinov), the parsley family (Apiaceae Lindl.) and the tarragon family (Asteraceae Bercht. & J.Presl), many of which are native to the Mediterranean. The culinary use of herbs has been textually documented in the eastern Mediterranean for over 3000 years. However, due to the nature of the archaeological record, where most macroscopic plant assemblages are preserved through charring, and the physiological characteristics of the plants themselves, herbs are largely underrepresented and have seldom been considered when assessing prehistoric culinary practices. Here, we present the results of a pilot modern phytolith reference collection of Mediterranean herbs to assess the potential of phytoliths in revealing ‘invisible’ plant ingredients in archaeological narratives. Phytoliths were observed in 48 of the 62 analysed reference samples. Although herbs are relatively poor phytolith producers, certain taxa produce distinctive morphotypes at different taxonomic levels that can potentially be used to identify the culinary uses of Mediterranean herbs in the archaeological record related to food preparation (e.g., residue analyses from food-processing artefacts, cooking vessels, charred food remains, etc.). In particular, anatomically connected silicified cells (silica skeletons) with potential taxonomic value were observed in species of the genus Mentha L. Moreover, species from the Apiaceae family, such as Daucus carota subsp. carota L. and Foeniculum vulgare Mill., produced massive multiseriate and pin-cushion trichomes with large multicellular stalks that could potentially hold taxonomic value.