Phytoliths in plants from the south coast of the Greater Cape Floristic Region (South Africa)

This is the first quantitative and morphological study of phytoliths from a diversity of plant species (56 spp., 23 genera and 14 families), growth forms (Restionaceae (restios) and Poaceae (grasses), bulbous plants, shrubs and trees) and plant parts (leaves, wood, scale leaves of the bulbs, culms and stems) from the Greater Cape Floristic Region (GCFR). The GCFR's south coast is an area with longest record of occupation by modern humans, and is thus of great archaeological significance. This study aims at building a phytolith reference collection of modern plants from the southern coast of the GCFR that are likely to have been used by past populations inhabiting the south coast of South Africa. A total of eighty phytolith morphotypes were identified in the whole data set. Poaceae and Restionaceae produced characteristic phytolith morphotypes that did not occur in other plant groups. Many other phytolith morphotypes occurred in more than one plant group. We confirmed that grasses are the highest phytolith producers. Restio phytoliths are unique characteristic of the Restionaceae and these are mainly derived from the parenchyma cells of the culms. The lack of diagnostic phytolith morphotypes that can be used for taxonomic identification in geophytes makes their identification difficult in the paleoanthropological record.