Historically wild rice was important economically and spiritually across much of central and eastern Canada, but the antiquity of its use by Native communities is unclear. Unlike plant macrofossils, which have traditionally been used to identify this plant in prehistoric contexts, silicophytoliths preserve well in archaeological sites and in carbonized food residue encrusted on clay pots. This proxy, therefore, promises to yield considerable new insight into the antiquity and intensity of wild rice harvesting in this region.
Various phytolith types from various grasses, sedges and aquatic plants were examined. However, the focus was kept on rondel phytoliths, a form only produced in grasses. Thirty-eight grass species were examined, including two species of wild rice (Zizania aquatica and Zizania palustris). A minimum of three hundred rondels from each grass species were counted from various parts of the plant including the inflorescence, the leaf and the stem. Based on extensive morphological comparisons of phytoliths produced by wild rice (Zizania spp.), and other native Boreal and Prairie grasses and maize (Zea mays), several phytolith morphotypes were identified that are produced only in wild rice (Zizania spp.). In general, rondels with four spikes, with one and three indentations, are characteristic of Zizania (spp.). However, differences between the two wild rice species were not established.
Lake sediments from Lulu Lake in the Lake of the Woods area where modern wild rice grows were analysed to determine if the types identified as being diagnostic of wild rice would be present. As a preliminary analysis, the presence of wild rice (Zizania spp.) can be identified in small quantities in lake sediments. Therefore, wild rice (Zizania spp.) phytoliths can be a powerful tool in the identification of the plant in Holocene sediments.
Potsherds with encrusted carbonized residues from the Lake of the Woods and surrounding area were also examined for the presence of diagnostic wild rice (Zizania spp.) and maize (Zea mays) phytoliths. These archaeological samples are attributed to the Laurel (Middle Woodland), Selkirk (Late Woodland), Blackduck (Late Woodland), and Sandy Lake (Late Woodland) cultures. Based on the use of diagnostic phytolith types for both wild rice (Zizania spp.) and maize (Zea mays), the presence of both these cultigens was identified in the residues of all four cultures mentioned above.
This is the first time maize (Zea mays) and wild rice (Zizania spp.) have been positively identified in prehistoric carbonized food residues from the Boreal Forest. Based on pottery types, wild rice (Zizania spp.) and maize (Zea mays) were consumed as early as the Middle Woodland period (Laurel phase). Based on the samples examined, the evidence of maize (Zea mays) phytoliths in the residue is greater than those of wild rice (Zizania spp.). However, this might reflect sample bias or most likely biases due to processing of the plants before consumption. Therefore, the absence of a wild rice (Zizania spp.) phytolith signature might not represent that the plant was not consumed, rather that the parts of the plant with the diagnostic phytolith types were removed before consumption.
Maize (Zea mays) horticulture during the Late Woodland period in the Lake of the Woods and surrounding area does not seem likely because there is no evidence of gardening, or heavy consumption of this plant. However, the latter might not be necessary for local horticulture. In contrast, wild rice (Zizania spp.) stands are common in the Lake of the Woods and surrounding area, and therefore local harvesting of this plant is inferred.
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