Comprehensive evaluation of morphological, anatomical, and palynological characteristics of some selected taxa of Zygophyllaceae in Egypt.

This study presents a comprehensive comparative analysis of six Egyptian taxa from the family Zygophyllaceae, representing the genera Fagonia, Zygophyllum, and Tribulus. An integrative approach was employed, combining morphological, anatomical, and palynological investigations using both light microscopy (LM) and scanning electron microscopy (SEM). The main objective was to evaluate the taxonomic significance of these characters and enhance species identification and classification within the family. Morphological assessments included leaf structure, floral and fruit morphology, and seed characteristics. Anatomical studies focused on the tissue organization of stems, petioles, and leaf blades, with emphasis on epidermal features, vascular patterns, and crystal distribution. Palynological analysis revealed significant variation in pollen size, polarity, aperture types, and exine ornamentation. A total of 219 characters were scored and analyzed statistically using Minitab software. Cluster analysis and dendrogram construction revealed a clear separation of Tribulus species from Fagonia and Zygophyllum simplex, which conversely showed closer affinities. These findings highlight the diagnostic value of integrating morphological, anatomical, and palynological data, and support the recognition of Tribulus at a distinct taxonomic rank within Zygophyllaceae. Collectively, these characters provide valuable tools for the accurate delimitation and identification of taxa at both generic and specific levels.