COMMUNITY NEAR FLAGSTAFF, ARIZONA

phytolith forms. Eight phytolith forms were identified, including a diagnostic phytolith for ponderosa pine, the spiny body. The general Poaceae subfamily system validated by numerous researchers is applicable to this community. Examination of phytolith shape frequencies show that for 7 species in the subfamily Pooideae, and 1 species in the Panicoideae, very few (0 to 5%) nondiagnostic phytolith forms were present. Nondiagnostic phytoliths, particularly rondels, were more common (7 to 22%) for the 3 species from the Chloridoideae subfamily. This result is consistent with the observation by other authors that all grasses produce rondel. forms and indicates that rondels will be over-represented in phytolith assemblages in comparison to actual vegetation. The ponderosa pine spiny body appears to be a useful diagnostic for this area and vegetation reconstructions using soil phytolith assemblages based on the system developed in this study could be used to understand grass-tree and grass vegetation dynamics.