Trichome and Pollen Morphology of Lycopus europaeus L. (Lamiaceae)

Background and Aims: Lycopus europaeus L. (Lamiaceae) is a perennial medicinal herb that grows in moist areas and produces white flowers. It contains many secondary metabolites, and L. europaeus has traditionally been used as a natural remedy for coughs, respiratory issues, and insomnia. This study aims to describe the hair characteristics of the stem, calyx, adaxial, and abaxial leaf surfaces, as well as the pollen morphology of L. europaeus.Methods: The plant was collected during its flowering stage from Bursa, between Bozüyük and İnegöl. Scanning electron microscopy (SEM) was employed for the micromorphological analysis of the trichomes and pollen of L. europaeus. The SEM images were captured using a Zeiss EVO 50 scanning electron microscope.Results: Covering hairs consist of nonglandular and glandular hairs. The nonglandular hairs are either unicellular or multicellular, characterized by cuticular micropapillae and composed of unbranched, elongated cells. The glandular hairs include peltate and capitate types. Peltate trichomes have a short stalk cell and a broad secretory head with 2-6 cells. Capitate hairs have a globose, unicellular head and a short, unicellular stalk. The plant's pollen grains are hexacolpate, featuring a reticulate exine structure and are prolate in shape (P/E 1.43-1.45 μm). The lumens appear round or nearly polygonal, measuring 0.05-1.27 μm in diameter. The width ranges from 0.10 to 0.55 μm.Conclusion: This study highlights two key features for identifying L. europaeus in detail: the morphology of trichomes and pollen.