Integrating morphometric and molecular data to reassess the taxonomy of Cyperus L. in Egypt: A revised classification

Abstract

The genus Cyperus L. (Cyperaceae) is one of the largest and most taxonomically complex genera within the sedge family, characterized by extensive morphological diversity and ecological significance. Despite its importance, the classification of Cyperus has been challenging due to convergent evolution, polyphyletic subgroups, and overlapping morphological traits. This study aims to reassess the taxonomy of Cyperus in Egypt by integrating morphometric and molecular approaches to provide a more robust and natural classification system. A total of 18 Cyperus species from Egypt were analyzed using 39 morphological characters (30 qualitative and 9 quantitative) and molecular data from five chloroplast markers (rbcL, matK, trnH-psbA, rpl32-trnL, and ndhF). Morphometric analyses, including hierarchical clustering and principal component analysis (PCA), revealed significant morphological variability among the taxa, with key vegetative and reproductive traits such as rhizome structure, culm characteristics, spikelet morphology, and achene traits proving critical for species differentia tion. Pea rson’s correla tion a na lysis identified rhizome scale, spikelet shape, and achene morphology as highly correlated with taxonomic distinctions. Phylogenetic analysis, combining morphological and molecular data, resolved the taxa into six main clades, strongly supporting the paraphyletic nature of the paraphyly of C3 Cyperus and the monophyly of C4 Cyperus. Notably, Cyperus alternifolius emerged as a distinct clade, while Cyperus fuscus and Cyperus difformis formed a well supported cluster. The integration of molecular data with morphometric results provided a clearer resolution of species relationships, highlighting the limitations of morphology-based classifications and the importance of combining multiple data sources for taxonomic revisions. Based on the findings, we propose a revised sectional classification for Cyperus in Egypt, dividing the genus into three main complexes: Papyrus, Cyperus, and Bobartia, each encompassing several sections. This study demonstrated the efficacy of integrating morphometric and molecular data to resolve taxonomic complexities in Cyperus, offering a model for future taxonomic revisions in other taxonomically challenging plant groups. The results contribute to a deeper understanding of the evolutionary history and diversity of Cyperus in Egypt, providing a foundation for further research and conservation efforts.