‘Sowing Seeds and Reaping Rewards’: relict plant studies at medieval castles

In 2020, the Castle Studies Trust funded Dr Karen Dempsey to undertake an innovative new line of research in castle studies, namely to explore the use of plants in castles in medieval Ireland. In this article, Karen explains what she and her colleague Dr Fiona MacGowan discovered.

Over the course of this Pandemic many people have a newfound or renewed appreciation for the green world that we live in. This might take material form by growing potted plants at home and if fortunate caring for a garden space of your own or somewhat less tangibly, the contemplation of changing seasons in your local park. The (anecdotal) health benefits we might feel from these activities are increasingly underscored by health professionals who assure us of the roles of green spaces in wellbeing. This connection is not a modern phenomenon – plants (and gardens) played a significant role in the diet, healthcare and spirituality of people living as part of castle households.

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Sowing Seeds of Interdisciplinary Work’, the Castle Studies Trust funded project, showed how relict plants can deliver new insights into everyday life at medieval castles. Relict plants – understood to be the descendants of plants grown, cared for and used by (medieval) people – were identified through botanical surveys at four geographically diverse but culturally similar medieval castles: Adare, Co. Limerick, Castleroche, Co. Louth, Carbury, Co. Kildare and Castlecarra, Co. Mayo (as detailed in my previous blog post). As an initial step in researching relict plants, particular attention was paid to archaeophytes, those plants which arrived in Ireland pre-1500 CE. I believed that these plants may have participated in the various colonisation processes of the twelfth century. Their introduction could be linked to new gardening and other health practices especially those related to novel plant medicines which were emerging across Europe at this time but were perhaps previously unknown in Ireland.

Relict Plant Findings

Botanical surveys began during mid-2020 in the very wet months of June and July after a hot May.

Over the course of the survey eight archaeophytes were revealed (Table 1) as well as a range of rare and common native plants. You can read Dr MacGowan’s botanical report here. These findings are significant: four of the eight plants were historically recorded as present in medieval gardens. The plants – comfrey, mallow, milk thistle and hedge mustard – are widely recognised as having medicinal properties (Fig 1). They feature in medieval recipes, continued as part of the tradition of plant medicine captured in Culpepper’s Herbal of 1653 and some, like milk thistle, remain in use today (see Table 1).

Figure 1 Milk thistle at Castleroche; Hedge mustard and Hemlock (Conium maculatum) at Carbury; (pictures by Dr MacGowan)

Table 1 List of Archaeophytes and neophytes at four selected castles in Ireland [1]

Figure 2 Castleroche, Co. Louth, sited for maximum spectacle across a locally significant elevation at the foothills of the Mourne Mountains

Relict Plants in their Castle Contexts

Castleroche was the first site surveyed for our fieldwork. It is spectacularly situated on a locally significant rocky outcrop, framed to the north by the foothills of the Mourne Mountains (Fig 2). The castle has been long understood as a defensive site, believed to have been positioned as authoritative infrastructure to exercise territorial control. Its’ patron, Roesia de Verdun (d.1247) is renowned as the only historically attested woman to have founded a castle in thirteenth-century Ireland This castle while now in ruins was once a busy place with an associated village replete with a weekly market and annual fair. I considered this site to have great potential for relict plants given that historic sources noted the presence of ‘gardinia’ (gardens associated with castles) coupled with the high-status of its’ patron who had a considerable number of estates across England and France. These connections must have given her and her staff access to, and knowledge of, different cultural traditions including gardening and medicinal practices. We were delighted to identify three archaeophytes: Hemlock (Conium maculatum), Mallow (Malva sylvestris) and Milk thistle (Silybum marianum). Milk thistle is a particularly important identification, it is very rare in Ireland and Britain. For medieval people, it was culturally and symbolically tied to the Virgin Mary as well as understandings of fertility and motherhood (Fig 3). This allows us to reconsider the idea of Castleroche only as a frontier site; perhaps there was a diverse resident population for much longer than previously understood. Their health concerns may be represented by the continued occurrence of these plants. Exploring the botanical legacy of Castleroche adds further layers to the story of this complex site.

Figure 3 The Unicorn Rests in a Garden (from the Unicorn Tapestries) 1495–1505. https://www.metmuseum.org/art/collection/search/70007568
Figure 4 Carbury, Co. Kildare: a multiperiod castle complex comprises a motte, an early masonry focal building with later additions including an Elizabethan extension crowned with multisided cut stone chimneys

A less well-known castle but equally deserving of attention is the medieval settlement at Carbury (Fig 4). This multiperiod complex comprises an earthwork castle, a twelfth or very early thirteenth-century masonry castle with later additions including an Elizabethan extension and related gardens (Fig 5). Carbury is entangled with generations of nobles. It acted as a central node in shifting political allegiances and dynastic disputes within the territory of Leinster. The longevity in occupation of Carbury is interesting, it attests – at least in part – to its suitability as a residence. Is this reflected in the immediate castle landscape? Is there a possibility that the early-modern gardens here overlay medieval predecessors? Four archaeophytes were found at Carbury: Hemlock, Comfrey (Symphytum officinale), Hedge mustard (Sisymbrium officinale) and White stonecrop (Sedum album), three of which were adjacent to or within the masonry castle and the fourth – Comfrey – which was found within the hedgerow that forms the historically significant boundary to the castle landscape (Fig 6). These plants are not uncommon, but perhaps their relative ubiquity is reflected in their suitability for use within different plant medicine traditions. Comfrey is particularly notable, known as knitbone, it was widely used as a healing poultice for broken bones throughout medieval medical texts. Pharmacologically, this plant contains allantoin, which promotes the creation of new cells and healing of connective tissue. Relict plant studies at Carbury allows us to reflect on how this place was a home to many different generations of people who participated in caring roles (for plants and people) whilst also being a locus for political tensions.

Figure 5 Aerial Imaging of Carbury Castle with evidence for potential gardens surrounding the castle.
Figure 6 Comfrey (Symphytum officinale) and Hedge woundwort (Stachys sylvatica) noted among other medicinal plants in hedgerow with Carbury Castle in background

With these exciting discoveries at both Castleroche and Carbury, we were very hopeful that the survey at Adare Castle would be equally rewarding. Adare was an important castle as the caput of the Geraldine family. Unlike the other sites, it has been subject to major study including detailed historical and archaeological investigation. Adare Castle was constructed on a pre-Norman power centre from which the castle emerged as a large D-shaped earthwork with a surrounding large ditch and river-fed moat (Fig 7). This later formed the inner ward, which was further enclosed by an external wall to the north-west with a single mural tower and a gatehouse to the south. The outer court is enclosed by masonry walling which is augmented by a ditch to the north and west. At Adare, the grounds are intensely managed, with manicured lawns and ongoing pesticide use (Fig 8). Unfortunately, this was particularly pronounced in the inner ward, the area I have suggested was likely to have contained an enclosed garden. Disappointingly, only one archaeophyte was identified: Weld (Reseda luteola). This dyeplant was predominantly used to give a bright colourfast yellow but also used medicinally to treat chest complaints. A number of neophytes – those plants whose introduction post-dates 1500 CE – were found in the associated areas surrounding the castle as detailed by Dr MacGowan. Species such as Himalayan pheasant berry (Leycesteria formosa) were identified, indicating that relict plants studies can also illuminate the afterlife of the castle when it  played a role as a romantic ruin in the eighteenth-century landscape of Adare Manor. This shows the potential for relict plants studies to add layers to castles stories across their life histories.

Figure 7 Plan of Adare Castle with possible garden (after Dempsey 2021 and O’Keeffe 2015)
Figure 8 Adare Castle, inner ward subject to extensive pesticide use

The final site, Castlecarra, falls lower down the social hierarchy of medieval Ireland than the other three castles but it was still an important baronial residence (Fig 9). It is situated on the eastern shore of Lough Carra. The castle now comprises a large three-storey focal building set within a very compact enclosure which is a later, potentially fifteenth-century addition. The castle was constructed as one part of the c. 1236 Anglo-Norman territorial expansion into Connacht. This site, like the others, has a long history of occupation. An early-modern (sixteenth-century?) house was constructed c. 125m NE of the castle, and the surrounding landscape appears to have been remodelled to suit a new tradition of landscape gardening which included a ha-ha and tree-lined avenue of Hornbeams (Carpinus betulus) (Fig 10). Archaeophytes were not recorded at Castlecarra but numerous native species as well as neophytes were present. This absence is remarkable but perhaps native plants at Castlecarra served the castle household needs. For example, Purging buckthorn (Rhamnus catharticus) was identified. This plant is native but rare in Ireland, and it was used medicinally as a purgative, as the name suggests. The botanical profile of Castlecarra leads to further questions around the transmission and sharing of medicinal and plant knowledge.

Figure 9: Castlecarra, Co. Mayo on shore of Lough Carra
Figure 10 Castlecarra, Co. Mayo: a multiperiod site with medieval castle that forms part of the landscape of an early modern (c. later 16th / early 17th house). Ordnance Survey Map 1925, Castlecarra to lower left and historic home including outbuildings and gardens centrally placed. https://maps.archaeology.ie/HistoricEnvironment/

Research, Heritage Futures and Reflection

One of this project’s aims was to test and refine the methodologies of relict plant studies for medieval castles. In Ireland there are currently 96 species recorded as archaeophytes (but with no established dates of introduction).  Despite the findings of some notable plants, the overall numbers of archaeophytes at the castle sites in ‘Sowing Seeds’ seemed low. Of course, our findings may have been constrained by single survey days, unseasonal weather as well as conservation and management issues – both present-day and historic. Future work is necessary. It is important that sites have the benefit of multiple visits across a wider seasonal survey period. Nevertheless, the baseline botanical surveys of this project will be of use for future research within and outside of castle studies. It has also revealed the need for a detailed survey of archaeobotanical evidence from excavations in Ireland to establish  as far as possible exact introduction dates for particular plants.

Including a wider range of plants and castles over a longer time span would provide comparative material with a greater capacity to capture change over time. Neophytes were noted in the botanical surveys but not part of the research agenda for ‘Sowing Seeds’. Their occurrence at castle sites may be revealing of expanding connections with sixteenth-century colonising and trading practices beyond Europe. Later medieval towerhouses are of particular interest as they are often situated within less managed and therefore within potentially better-preserved landscapes. But equally, native plants should also be included. For example, self-heal (prunella vulgaris) and pellitory-of-the-wall (Parietaria judaica) occur widely and were both used as medicinally. It would be of great interest to compare and contrast different plants at castles whether native, anciently introduced or more recent. Consideration too could be given to the afterlives of medieval castles as romantic ruins as indicated at Castlecarra and Adare. This would develop a wider appreciation of the long lives of medieval castles that continue in dialogue with contemporary communities as heritage today. Relict plant studies enable castle studies to participate in emerging conversation around green heritage and climate change.

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‘Sowing Seeds’ was a novel project – both conceptually and methodologically – I wanted to find a way to explore potential ‘green identities’ of castle households. Accessing the relationships medieval people may have had with their environments (as we might term it today) offers a different way of telling stories about the medieval past whose narratives are often caught into concerns of power, authority or control. By including botanical surveys of relict plants in castle landscapes, we have expanded further the multidisciplinary approach of castles studies. We can show how stories of castles are richly textured: populated by many people and plants over the course of their lives and beyond into their afterlives as romantic ruins and archaeological monuments. Doing this for the first time meant engaging with new material and unfamiliar sources from archaeology, history, and medical knowledge to heritage and folklore. This wide-reaching research methodology is a core strength of this project. It enables a dialogue between different disciplines that are traditionally separate or rarely integrated. These findings are a beginning: they encourage new avenues of future research on castles households relating to human-plant relations, plant medicine and related concepts of care. The results also invite conversations with heritage agencies regarding site management and conservation practices of both biodiversity and past vegetation. Rather than offering conclusive findings, we have revealed tantalising hints and a vast array of potential new avenues in which to take this research.

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This research was generously funded by the Castle Studies Trust. Their support enabled new ideas to be explored. As an early career researcher being awarded a grant to undertake (potentially) interpretatively risky work is a wonderful opportunity.

Helpful commentary and feedback was received from two assessors whose insights improved this report.

Thanks to Dr Fiona MacGowan for participating in this research project and carrying-out the botanical surveys at the selected sites.

Thanks to the landowners of Castleroche, Castlecarra and Carbury, and the Office of Public Work who manage Adare, for access to the sites for this project.

[1] Dates in the table refer to the first historic botanical record of these plants in Ireland and Britain, and * denotes their occurrence in lists of species included in medieval gardens (Harvey 1981)

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