Revealing Coix lacryma-jobi var. lacryma-jobi (Job’s tears) in Han Dynasty burials with evidence from phytolith identification

<em>Coix lacryma-jobi</em> L. (Job’s tears, adlay, yiyi 薏苡in Chinese) is a tropical member of the Poaceae family which is widely grown in southeast Asia for its grain, as medicine and for beads. However, archaeobotanical evidence of <em>Coix</em> from macrofossils or phytoliths remains limited, and the varieties used in ancient China have yet to be identified through research. In this study, the remains of involucral bracts of <em>Coix</em> from two Han Dynasty tombs (2004CSX Tomb M110 and RNSM Tomb M1, dated to around 2,100 cal BP) in Xi’an, Shaanxi Province, China, were examined. Macrobotanical analysis suggested they were <em>C. lacryma-jobi</em>, and phytolith analysis further confirmed their identification as <em>C. lacryma-jobi</em> var. <em>lacryma-jobi</em>. This is the first report to successfully identify ancient remains of this plant to variety level from phytoliths. The findings provide new insight into the cultural significance of <em>Coix</em> in Han Dynasty funerary customs and demonstrate the potential of phytolith analysis for the identification of taxa from archaeological contexts to variety.<br>