Ayoub Molaahmad Nalousi

Orchids, belonging to one of the most diverse plant families, exhibit remarkable ecological and morphological diversity, making them a fascinating subject for scientific studies. This research focused on 15 species of terrestrial orchids collected from diverse habitats in Iran, aiming to assess the morphological diversity of their seeds and its implications for phylogenetic relationships and conservation. The study employed scanning electron microscopy (SEM) to evaluate 16 morphological traits, including seed length (SL), cell length (CL), cell width (CW), and embryo volume (EV), among others. These traits were analyzed using statistical approaches such as correlation analysis, clustering, and principal component analysis (PCA). The results highlighted significant variability among the species, with seed length ranging from 260 µm to 680 µm and embryo volume varying from 0.02 mm³ to 0.08 mm³. Strong positive correlations were observed between seed and embryo dimensions, particularly between seed volume (SV) and embryo volume (EV), with a correlation coefficient (r) of 0.92. Clustering analysis grouped the studied species into distinct clusters, with species from the genus Ophrys forming a separate group due to their unique seed characteristics, such as high embryo-to-seed volume ratios. The PCA revealed that the first three components explained 73.6% of the total variance, with seed length, cell length, and embryo dimensions being the most influential traits. Notably, the Ophrys species demonstrated substantial interspecies morphological diversity, reflecting their unique evolutionary adaptations. Furthermore, the morphological variation observed among other species, such as Orchis anatolica and Gymnadenia conopsea, highlighted both phylogenetic relationships and ecological influences on seed morphology. This study underscores the importance of seed morphological traits as reliable markers for distinguishing closely related species and understanding their phylogenetic relationships. Although morphological analysis has limitations due to environmental influences, the integration of advanced statistical methods such as PCA and clustering provided a comprehensive framework for analyzing genetic diversity. These findings not only enhance our understanding of terrestrial orchid diversity but also contribute to their conservation by providing critical insights into species differentiation and genetic management strategies. Future studies should incorporate genomic tools alongside morphological analyses to develop a more robust understanding of orchid evolution and adaptation.