Morphological Classification of Grass Phytoliths

Abstract Opal phytoliths derived from epidermal cells of grass leaves have been identified in atmospheric dust, soils, paleosols, Pleistocene loess, and deep‐sea sediments. By comparing oriented shapes of phytoliths in spodograms of 17 common grass species, four classes and 26 types are proposed which distinguish three groups of subfamilies of Gramineae. The Festucoid class contains eight types that are circular, rectangular, elliptical, or oblong forms. The Chloridoid class contains two types of saddle‐shaped bodies. The Panicoid class contains 11 types that are variations of crosses and dumbbells. The Elongate class contains five types that have no subfamily implications and occur in all 17 species. Because phytoliths of native tall grasses (Panicoid), short grasses (Chloridoid), and common domestic grasses of the humid regions (Festucoid) can be distinguished, it is possible to determine whether phytoliths in dust, soils, and sediments were derived from local or remote sources.