Phytolith studies in native ferns from Southern South America

Abstract Amorphous silica phytoliths are produced in a very diverse group of plants. Due to their taxonomic significance and high preservation state in ancient sediments, they have been used as indicators of past plant communities and environments. However, ferns have been scarcely studied with regard to phytoliths, especially in southern regions. In this study, we analysed phytolith production in 14 native species from the Pampean Plains to determine which morphologies are diagnostically relevant for palaeobotanical interpretations, assess phytolith abundance in these ferns, and examine their relationship with systematics and environmental conditions. Phytoliths were extracted from leaves using a calcination technique, and their content was estimated. Eight ferns from five different families produced identifiable phytoliths, mainly derived from epidermis tissue silicification. Some morphologies may be considered diagnostic, such as Elongate sinuate in Adiantum spp., Spheroid rugose in Woodsia montevidensis, Spheroid psilate in Blechnum auriculatum, and Conical and Elongate papillar in Anemia tomentosa. The silicification process seems to be consistent at the family level; however, some discrepancies with previous studies demand further study. Finally, the results suggest some links between phytolith production and habitat conditions, especially concerning soil humidity and sun exposure.