Phytolith analysis is rapidly maturing into a robust and powerful palaeobotanical data system. Many plant groups can be identified to family or subfamily, and even species identification has been suggested. Distinctive phytoliths occur abundantly in members of the grass family and are also found in several other groups including rushes, sedges, palms, conifers, deciduous trees, and other dicotyledonous plant taxa. Soil phytolith assemblages have provided palaeobotanical data on the order of thousands to millions of years ago. Moreover, as test cases for analysis in soil have increased, an emerging pattern indicates that phytolith populations are stable decay-in-place residues following deposition in sediments. Phytolith studies reflect both macroecological as well as subtle microecological, ecotonal differences, and/or very specific ethnobotanical and cultural activities. Phytolith analysis is a superlative source of botanical information in narrowly defined contexts of archaeological sediments.