A comparative analysis of wet and dry ashing techniques for the extractionof phytoliths from plant material

Two methods are commonly used for the extraction of phytoliths from plant m aterial to be used as reference int he analysis of archaeological phytolith samples: (1) spodograms or dry ashings; and (2) acid digestions or wet ash ing. It has been suggested that these techniques may modify the resultant s amples in different ways. Dry ashing, in particular, has been implicated as a cause of shrinkage and warping in phytolith assemblages when incineratio n occurs at greater than or equal to 450(0)C. The results of a morphometric comparative analysis between the dry ashing and wet ashing methods do not support these claims. This study establishes the differences in patterns of dimension and curvature of short bilobate phytoliths and of elongate phyto liths both subjected to dry and wet ash preparation are not statistically s ignificant. There is, therefore, no detectable evidence of morphological im pact as a result of these methods. This finding implies that any difference that do occur in phytolith size and curvature are typical, possibly random permutation within assemblages, or that they are the result of variation i n leaf cell structure rather than the consequence of a particular extricati on procedure. This suggests that the practice of using different methods of preparation of reference samples for fossil analysis can be reliably conti nued.