Some anatomical and palynological characteristics of Onobrychis paucijuga Bornm. (Fabaceae)

AbstractPurpose: The present study aims to provide some anatomical and palynological characterization of the endemic species Onobrychis paucijuga Bornm. and to assess its taxonomic significance within the genus.Method: Root and stem anatomical structures were examined using light microscopy. Hand sections obtained from plant materials preserved in 70% ethanol were mounted in glycerin–gelatin and analyzed under a Nikon Eclipse 80i microscope. Pollen morphology was investigated using both Wodehouse and Erdtman methods. In addition, scanning electron microscopy (SEM) was employed to examine exine ornamentation and surface ultrastructure.Findings: The root exhibits a well-developed secondary structure with a multilayered periderm, a wide cortex composed of parenchymatous cells, and a distinct vascular cambium separating the secondary phloem and xylem. Sclerenchymatous fibers occur in the cortical region and near the phloem. The stem shows a typical dicotyledonous structure with a collenchymatous hypodermis, multilayered lacunar collenchyma, and well-developed vascular tissues. In older stems, pith parenchyma cells tend to disintegrate. Pollen grains are radially symmetrical, isopolar, and tricolpate. Based on the P/E ratio, they are prolate in the Wodehouse preparation and subprolate in the Erdtman preparation. The exine ornamentation is reticulate-granulate, and the exine is tectate, with a thin tectum. SEM observations confirmed the reticulate-granulate exine ornamentation and revealed detailed surface structures.Conclusion: The anatomical and palynological features of O. paucijuga are largely consistent with those reported for other members of the genus Onobrychis and the family Fabaceae. The combination of anatomical and pollen morphological characters provides valuable diagnostic traits for the identification and taxonomic evaluation of this endemic species.