Identifying the plant materials in Te Rā

TeRaRanui copy 2Figure 1 Ranui Ngarimu with Te Rā at the British Museum, London, January 2019

Over the last 15 years part of my work as a conservator of cultural materials and textiles researcher has been to try and develop ways to identify the plant materials in artefacts. Why is this important, or even necessary? Most of the artefacts made from plant materials in museums have little or no provenance, or information about who made, wore or used them, so identifying the plants they are made from can help determine who the original owners are. More than that, artefacts made from plant materials are often textiles (basketry, string, nets, traps, bags, dress).  When we know what textiles are made from we can learn so much more about the societies that produced them-their relationships, trade patterns, hierarchies and complexities.

It is also important to be able to identify the plants used in Māori textiles for a number of specific reasons. Māori arrived in New Zealand sometime in the 13th century from East Polynesia in an extraordinary feat of ocean-going navigation. New Zealand was the last landmass settled by humans, and the last landfall in the systematic navigation of the Pacific by Polynesians.

TeRaPacific

Figure 2  Settlement of the Pacific ©CC 3.0 David Eccles

Polynesians settlers typically travelled with a kind of portable economy, sometimes called ‘transported landscapes’ in their canoes, so that when they arrived in unknown territory, that had some animals and plants available to them to start their new lives. However, when Māori arrived in New Zealand, the climatic change was such (from tropical to temperate) that the standard Polynesian textile plants failed, and it was necessary for Māori to quickly adapt their textile production to new plants endemic to New Zealand. Understanding plants and being able to make textiles from them is essential to life – something that we forget in contemporary society because we are so separated from the production of textiles. Without textiles (line, cord, string, nets, bags, baskets) you can’t catch, keep or carry food, aside from the requirements for clothing that can protect you and enable your physical activities.

The plants used to make Māori textiles are therefore physical evidence of adaptation to plants endemic to New Zealand, and also evidence of the technological revolution required so that Māori could survive in Aotearoa. Understanding the diversity of plants used by Māori also increases our knowledge of the cultural changes Polynesians went through after their arrival in Aotearoa.

TeRaHarakekeFigure 3 Pā harakeke, Orokonui Ecosanctuary

Identifying the plants in artefacts would seem a fairly straightforward activity, however turning plants into textiles usually involves processing them (such as splitting, pounding, removing fibre, boiling, retting, dying) which in most cases removes the features of plants that a botanist would usually use to identify them. In the case of the most used New Zealand textile plants, all of them are monocotyledons, meaning that they are structurally very similar. Another confounding factor is that plants are incredible variable materials- because they can grow under diverse weather conditions across a geographic range, even plants of the same species can be quite different from one another.

TeRaPLMFigure 4 Polarising Light Microscope used to identify plants

The best way we have found so far to identify New Zealand textile plants is using a Polarised Light Microscope (PLM) to compare unknown specimens to a set of identified reference materials. There are numerous advantages to using PLM. PLM is readily available in many museums, and it is a technique that has been used more broadly in textiles identification for a long time, and consequently has extensive supportive literature about its use. Those with microscopy experience find that learning how to use PLM is not too difficult.

TeRaSampleEppFigure 5 Example of sample used to identify plant materials using PLM

The sample size required is very small, and in the image above you can see how small a piece of fibre or leaf material sample for PLM is. Using PLM involves identifying features at the cellular level which adds another very important advantage–most processing methods used to transform plants into artefacts do not seem to destroy the features apparent at the fibre cell level. So even if the plant material has been heavily processed, or if there is only fibre available, we have a good chance of being able to identify it using PLM.

One of my jobs when we visited Te Rā at the British Museum in January 2019 was to remove small samples from all parts of the sail so we could identify the plants she is made from. This involved gaining permission from the Scientific Research Committee from the British Museum well before we arrived, using the justification of our research question (it’s not good to take samples from artefacts unless you know why you are doing it, and whether there is a question worth answering from undertaking analysis), and our validated previous results (or in other words whether we were justified in taking samples because we knew we could find an answer). We also had to stringently document where we were taking samples from. I gained permission to take 15 samples of plant material from Te Rā, and you can see where they were taken from in Figure 7 below.

The tiny pieces of plant material and fibre were placed in eppendorphs, or small capped vials, and then sealed in two layers of plastic sealed with yellow biohazard tape, before being packaged into envelopes for import into New Zealand. There is a stringent biosecurity process for bringing even these small dessicated pieces of plants into New Zealand, even though they were originally imported to Britain from here!

 

TeRaPackaging.jpgFigure 6 Packaging up samples for import into New Zealand

TeRaPlant samples copy 2Figure 7 Sample locations, Te Rā

Once safely in the containment facility at the Department of Botany, University of Otago, the samples from Te Rā were placed in the freezer for several weeks before we were able to process them.

 

teRaSamples1Figure 8  Processing the samples from Te Rā, Department of Botany

The samples were removed from their packaging, cut in half, and placed in new eppendorphs – this way, if anything goes wrong we have more material to re-examine. The samples are then covered in a bleach solution (1.25v/v sodium hypochlorite in distilled water) to break the plant material down into ultimate fibres. To hasten this process, the eppendorphs containing the samples and the bleach solution are placed into a water bath which is heated to 60°C for two hours (we use a ‘fancy’ home-made polystyrene float to suspend them in the water bath).

TeRaSample3Figure 9 Water bath with eppendorphs

Once out of the water bath, we placed the eppendorphs in a centrifuge, so that the ultimate fibres would collect in one place, so during rinsing with water we keep as much of the sample as possible. We haven’t done this step before, but the samples from Te Rā are so precious and important.

 

teRaSample5Figure 10 Dr Bronwyn Lowe loading the samples in the centrifuge

The samples were rinsed three times, then left to dry so that we can then mount them on microscope slides for viewing under the microscope. After drying they’ll look something like this:

 

TeRaEppProcessedFigure 11 Dried, macerated ultimate fibres in an eppendorph

When we look at the ultimate fibres using the PLM, we look for a number of diagnostic features for each New Zealand textile plant. Some of these features are about the morphology of the fibres (shape, pits, dislocations, ends, length), some features are about the optical properties of the fibres – how they look when exposed to polarized light and tested in various ways.

Here are some images of some of the typical features of some of New Zealand’s textile plants using polarized light microscopy:TeRaHarakekePLM

TeRaTikouka

TeRaKiekie

The next step for us is to spend a couple of weeks making microscope slides of the samples of Te Rā, and systematically studying them under the polarizing light microscope. Two of us will be working on the identification, so we can independently verify our results.  All going well,  by the end of this process we will know the plant, or plants, that Te Rā is made from, important information for our weavers, and for expanding our knowledge about Māori sail technology.

By Catherine Smith

If you want to read more about the different ways me and other researchers at the University of Otago have tried to identify plants in Māori artefacts see this link:

https://www.researchgate.net/publication/315382507_Advances_in_conservation_of_Maori_textiles_analysis_and_identification

If you want to read the scientific articles we have published about different methods of plant identification see this link:

https://www.researchgate.net/publication/313484465_Polarized_Light_Microscopy_An_Old_Technique_Casts_New_Light_on_Maori_Textile_Plants

Or this one:

https://ourarchive.otago.ac.nz/handle/10523/7280

 

 

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