Revised taxonomic interpretations of Cyperaceae phytoliths for (paleo)botanical studies with some notes on terminology

Abstract

This paper comprises two complementary parts. Firstly, phytolith morphology results from 17 species in 8 genera (Cyperus, Eleocharis, Fuirena, “Mariscus,” “Pycreus,” “Schoenoxiphium,” Scirpoides and Scleria) that were drawn from phytolith analysis of 36 sedge species from 13 genera are presented for their importance in the taxonomically problematic Cyperaceae. Secondly, we provide a synthesis aimed at bridging the current disconnect between phytolith analyses in paleobotanical studies and botanical studies which also seem to recognize plant silica differently. We found that results which were thought to be novel for paleobotanical studies have already been documented by taxonomists. To this end, commonly used terms such as “Cyperus/Kyllinga-type” and “Scirpus-type” in paleobotanical studies are not consistent with sedge taxonomy and need to be revised to adapt to new sedge classifications. We present supporting phytolith morphology evidence. We report likely the first known evidence of the presence of the Carex-type phytolith morphotype in the African genus “Schoenoxiphium.” Among others, our phytolith data support the generic classification of Scleria and provides tentative support for the recent suggested close relationship between Fuirena and Eleocharis by molecular studies. Although this study is limited in scope and the fact that the presence of the same unique morphotype in different taxa does not necessarily imply that they are closely related since they may exhibit homoplasy, our data are a preliminary step on how phytolith morphology may contribute to understanding relationships in Cyperaceae, a character that has long been used by taxonomists.