Archaeobotany has been a key part of archaeological science since the 1970s, and although the tried and tested techniques that form the basis of this study area (basically playing with buckets, water and sieves) have remained unchanged for decades, the research field continues to give new insights into the past as new sites and periods are studied. Archaeobotany (or palaeoethnbotany in America) usually refers to the study of plant macrofossils – seeds, fruits, leaves, twigs, nuts etc. Basically any plant remains which can be seen (just about) with the naked eye. Plant microfossils – starch and phytoliths, also come under the umbrella of archaeobotany, but I’m going to stick to the big bits here.
Plant macrofossils are all retrieved by either flotation – breaking up anywhere between 1-40L of sediment in a tank of water, and collecting the plant remains which float on the surface, or sieving – passing the sediment through a stack of sieves. The flot or sieve residues are then studied under a low power microscope, usually only up to x40 magnification. Archaeobotanists study plant remains preserved by four main types of preservation. These are very important to keep in mind, as they effect which seeds are preserved in the first place, how the seeds are separated from sediment, how hard it is to identify the seeds, and what type of information they are going to give us about past societies.
Second – mineralised plant remains. This is a pretty rare type of preservation. It normally occurs in cesspits, when calcium (from animal bones, marine shells, egg shells etc.) and phosphate (from human waste) enter into seeds/fruit stones, and form calcium-phosphate. This material will survive for millennia, but the range of casts and impressions formed (individual cell replacement, interior casts, exterior casts) can be tricky to identify. Nevertheless, mineralised plant remains provide us with fantastic evidence for diet and trade in plant foods, mainly for the Roman and Medieval periods.
Third – desiccated plant remains. In hyper-arid places (think Egypt) the bacteria which would usually decay plant remains cannot do so without any water. So, huge quantities of straw, cereal chaff, fruit stones and seeds survive in middens, mud bricks and in occupation deposits within buildings. Studies at trading settlements on the Red Sea have provided fascinating evidence for spices which were traded from India to the Mediterranean, and also more everyday activities like animal foddering and crop-processing (Van der Veen 2007).
Finally, waterlogged plant remains are in a way most similar to desiccated plant remains, but decay is stopped in this case by the lack of oxygen rather than water. Plant remains have to have been dumped into the standing water at the bottom of deep pits or wells, or discarded in towns with damp climates (like York!) where the rate of organic rubbish dumping was faster than decay. Waterlogged plant macrofossils are also preserved in off-site sequences, such as peat bogs and palaeo channels. The study of these usually falls under the realm of palaeoenvironmental studies.
The great thing about waterlogged plant remains is that they include plant foods which do not need to be exposed to fires during food preparation – like fruits, flavourings and vegetables. So, waterlogged samples typically produce a much more diverse range of plant foods than charred samples from the same site. Plus, waterlogged preservation is much more common than mineralisation in north-west Europe.
My research focuses on the development of “oppida” in the Late Iron Age and into the Roman period, and what the societies were like which inhabited these settlements. Whilst sampling for plant macrofossils has been widely undertaken for around 40 years, no oppida has been excavated during this period in a large enough scale, or with enough attention to systematic sampling (large well-recorded sediment samples from a wide range of deposits and site phases). So, we don’t know what foods the inhabitants were eating, and whether what crops they grew, and how they grew them, had to change as people decided to live in the first proto-urban settlements in Britain.
Luckily, the University of Reading Silchester Insula IX ‘Town Life’ Project has been excavating a large area of the oppidum Calleva Atrebatum over the last two decades. The reliance on wells for water supply to the settlement in the past, combined with the bulk sampling for plant remains throughout the excavation, meant a large dataset was available for study. Two Late Iron Age wells contained waterlogged plant remains. Whilst most of the sample consisted of seeds of weedy plants, which would have been growing around the mouth of the well, around 5% of the sample contents were seeds of cultivated plant foods. Several seeds of celery and coriander were present, alongside a few pieces of olive stone. These foods were previously thought to have been introduced to Britain by the Roman military after the Roman Invasion in AD 43, but we now know that some of the inhabitants of Late Iron Age Silchester were selectively adopting some of the plant foods being consumed elsewhere in the Roman world.
The archaeobotanical dataset from Insula IX also includes substantial charred and mineralised datasets, showing both continuation and change in farming and food consumption practices across centuries of occupation there. Whilst my research so far has focussed on the systematic application of long-standing archaeobotanical techniques, the development of new methods of statistical analysis, combined with exciting developments in the areas of crop stable isotope and aDNA analysis, means archaeobotany continues to provide new insights into the past.
Lodwick, L. (2014). Condiments before Claudius: new plant foods at the Late Iron Age oppidum at Silchester, UK. Vegetation History and Archaeobotany 23: 543–549.
Van der Veen, M. (2007). Formation processes of desiccated and carbonized plant remains – the identification of routine practice. Journal of Archaeological Science 34 (6), 968–990.
About the Author
Lisa Lodwick is a Post Doctoral Researcher at the University of Reading, her current research focuses on analysis of plant macrofossils from Silchester. Lisa completed a BA in Archaeology and Anthropology and an MSt. in European Archaeology at the University of Oxford, before pursuing a PhD in Archaeology at the same institution. Lisa’s PhD research focussed on agricultural and social changes during the Late Iron Age to Roman transition period in Britain, identifying changes and continuities in consumption and production patterns. She occasionally blogs about her own research at https://theplantremains.wordpress.com/ and tweets much more frequently about archaeobotany @LisaLodwick . Lisa is also one of the team behind the successful Not Just Doormice – Food for Thought blog https://notjustdormice.wordpress.com/.