Comparison of Seed Morphology and Seed Coat Chemistry in Ophrys (Orchidaceae) Species

Abstract

Orchidaceae is the largest flowering plant family in the world and holds significant importance in terms of biological diversity. Many of the species are found in endemic regions, serving as important indicators for the conservation of biological diversity. Therefore, research on the morphology, seed and embryo structures, chemical composition, and taxonomy of orchids is crucial for species conservation, habitat restoration, and the sustainability of natural habitats. This research involves comparing the morphometric and chemical contents of seeds belonging to certain Ophrys L. species and examining interspecies relationships. The micromorphological features of the seeds were analyzed by using light microscopy and scanning electron microscopy (SEM), while their chemical contents were compared by using Fourier transform infrared spectroscopy (FT-IR) analysis. Seed and embryo morphology, morphometric analysis, and seed coat chemistry hold diagnostic significance. In species of the Ophrys genus, features like anticlinal wall structure and periclinal wall reticulation are considered weak taxonomic characters. FT-IR analysis identifies specific chemical groups in orchid samples, revealing significant differences in absorbance values and chemical compositions among the different orchid species. Particularly, Ophrys lycia (Lycian Kaş Orchid) shows distinct separation from closely related species at peak points such as 2917 and 2850, 1743, 1515, 1240, and 1031 cm–1. Common peak points in the fingerprint region (1200– 700 cm–1) indicate similarity between O. apifera and O. reinholdii subsp. reinholdii. O. ferrum-equinum, O. mammosa subsp. mammosa, O. fusca subsp. leucadica, O. reinholdii subsp. reinholdii, and O. iricolor exhibit similar absorbance values in the range of 1500–1000 cm–1. These results provide valuable preliminary information about the structure of orchid seed coats, reticulation presence and pattern, chemical profiles, distribution, and dormancy-germination processes.