Plant macro remains from the 1st and 2nd Cent. A.D. in Roman Oedenburg/Biesheim-Kunheim (F) : methodological aspects and insights into local nutrition, agricultural practices, import and the natural environment

The Roman settlement Oedenburg was founded at the beginning of the 1st Cent. A.D. in the lower plains of the river Rhine between the present-day communities of Biesheim and Kunheim in Alsace, France. The archaeology of the Roman settlement is very complex; it comprises two successive 1st Cent. A.D. military camps, a civil agglomeration including a large temple complex (dated from the 1st to the 4th Cent. A.D.) and a Late Roman occupation; a large part of the archaeological structures are located under the present groundwater level which has resulted in excellent conditions of preservation through waterlogging. The archaeobotanical analysis focuses on structures of the Roman civil agglomeration with special consideration of the temple complex; as well as few structures from the military camps. The main goals of this study were: to find out more about local nutrition, import, the natural environment and agricultural practices in Roman Oedenburg; and to explore methodological aspects in archaeobotany.
The analysis of plant macro remains (mainly seeds and fruits) has revealed a rich and diverse plant spectrum of cultural plants as well as wild plants. In total 303 plant taxa were identified; they were preserved mainly through waterlogging (292 plant taxa), besides mineralisation (57 plant taxa) and charring (58 plant taxa).
The plant assemblage illustrates that the inhabitants of Roman Oedenburg had access to a wide variety of vegetable food. The main part of their basic diet consisted of cereals and pulses; their dishes were seasoned with typically Roman condiments, while fruits and nuts from both local and foreign sources were regularly consumed. In comparison to other sites in the Upper Rhine region and the North of Switzerland, the list of food plants in Oedenburg is extensive and varied, which can be linked to the military occupation of the site and after that with its function as a centre of distribution.
Many imported plants have been attested, the majority originate from the Mediterranean region, and only some are from further distances. They include: pepper (Piper nigrum), black cumin (Nigella cf sativa), olive (Olea europaea), date (Phoenix dactylifera) and stone pine (Pinus pinea) among others.
The many riverbank, reed, and aquatic plants found within the archaeological structures demonstrate that the settlement area was characterised by a moist environment with open and slowly flowing water. In addition, the numerous findings of cereal remains, arable weeds and grassland vegetation point towards an open landscape of cereal fields, meadows and pastures in the near vicinity.
Based on the arable weeds, it is concluded that the agricultural practices carried out in Roman Oedenburg involved: the exploitation of garden plots for the cultivation of vegetables, spices, and pulses; the management of grassland; and the cultivation of both summer and winter cereals. The presence of large quantities of weeds belonging to the Order of the Secalietalia, Caucalion alliance was noted; of which the most frequently found species is muskweed (Myagrum perfoliatum). The greater part of these weeds of winter cereals is native in the Mediterranean region. It is hypothesized that they reached the site as part of imported cereal stocks from the Mediterranean.
The majority of archaeobotanical assemblages found in Roman Oedenburg derive from mixed deposits; yet there is evidence of waste disposal, wetland management and offering practices. It was establish that some plants found as part of the vegetable offerings in the temple complex in Roman Oedenburg were exclusively used for sacred practices (e.g. date and stone pine).
Finally, a methodological issue was explored. It consisted of finding a suitable pre-treatment method for the processing of very compacted waterlogged organic sediments. Experiments with four known pre-treatment methods have revealed that freezing and de-frosting a soil sample before sieving enhanced the sieving process and least damaged the plant macro remains.