A preliminary comparison of the short cell phytoliths from Zea mays, Pennisetum glaucum, and Sorghum bicolor subsp. bicolor leaves

Abstract

• Morphology and length and width measurements are used to establish the diagnostic value of the phytoliths produced by three crop species. • Pennisetum glaucum and Sorghum bicolor subsp. bicolor short cell phytoliths cannot be differentiated from those produced by wild southern African grasses. • Zea mays variant 1 crosses are diagnostic and can be used to establish crop presence at pre-colonial archaeological sites in southern Africa. • More research into phytolith morphometrics is needed to understand phytolith diagnostic value. While numerous studies have investigated the phytoliths produced by maize ( Zea mays ), an exotic crop introduced into southern Africa during the Columbian exchange (1492–1800), our research has the potential to impact the field significantly. No previous study has been published on whether maize phytoliths can be differentiated from those created by wild and domesticated plants from southern Africa. This research is crucial in understanding whether maize phytoliths can be used as a proxy for crop usage at archaeological sites in southern Africa. In this paper, we present the results of our analysis of the leaf phytoliths of landraces/cultivars of African domesticates, specifically pearl millet ( Pennisetum glaucum ) and sorghum ( Sorghum bicolor subsp. bicolor ) , and exotic crops, namely maize . We explore the similarities, and differences between the short cell phytoliths produced by these crops and the wild southern African grasses closely related to them. Our data show that based on size, variant 1 cross phytoliths can be used to distinguish between maize, the African grain crops used by pre-colonial farming communities and the wild southern African grasses related to them.