Integrating morphological and phytochemical characters in understanding the taxonomic relationship within some...

Ipomoea is a large and diverse genus within the family Convolvulaceae, widely utilized for ornamental, nutritional, and medicinal purposes. The genus exhibits considerable variation in stem and lamina structures, reflecting its ecological diversity and growth habits. This variability has contributed to taxonomic uncertainty at the infrageneric level. The present study aims to identify diagnostic morphological characters of the stem and lamina in eight Egyptian wild and cultivated Ipomoea species, and to evaluate their secondary metabolite profiles to assess their taxonomic significance. Macro- and micromorphological characters were examined using light and scanning electron microscopy. Phytochemical profiling was conducted using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), supported by molecular networking analysis.

Several macro- and micromorphological characters were diagnostic at the species level, including plant habit, leaf composition, lamina shape, nectary gland, trichome type, vascular system, pith type, and secretory cell distribution. Furthermore, LC-ESI-MS/MS supported by molecular networking led to the annotation of 132 metabolites, of which 107 were secondary metabolites, substantially expanding the known chemical profiles of the studied species. Notably, this study provides the first comprehensive chemical description of Ipomoea ochracea. Finally, integration of morphological and phytochemical data into a dendrogram revealed a coherent hierarchical structure reflecting varying degrees of affinity among the species. Remarkably, I. tricolor was distinctly separated from the remaining species, which formed a large cluster further subdivided into two major groups.

These findings demonstrate that the combined characters provide reliable and complementary criteria for species delimitation within Ipomoea, highlighting the significance of integrative approaches in plant systematics. Further studies incorporating additional datasets, particularly molecular analyses based on chloroplast and nuclear DNA markers, are recommended to achieve a more comprehensive understanding of relationships within the genus.