Labellum micromorphology of some orchid genera (Orchidaceae) distributed in the Black Sea region in Turkey

Abstract

A detailed micromorphological analysis of the labellum was carried out using both light and scanning electron microscopy on 14 genera (Anacamptis, Cephalanthera, Coeloglossum, Dactylorhiza, Gymnadenia, Himantoglossum, Limodorum, Neottia, Orchis, Ophrys, Platanthera, Serapias, Spiranthes, and Steveniella) of Orchidaceae in Turkey. In the samples, various epidermal features were identified in the spur that developmentally are invaginations of the labellum and the adaxial surface of the labellum. Typical secretory cells and inclusions such as starch or calcium oxalate crystals of different sizes and shapes were found within the structure of individuals. In many genera, characteristically shaped secretory trichomes and papillae were concentrated at the base part close to the gynostemium or the distal part of the labellum and on all surfaces of the spur. In the genus Ophrys, the labellum surface was covered with many hairs. Furthermore, the labellum surface striation varied among the orchid genera. UPGMA of cluster analysis was used to evaluate the morphological and micromorphological features of the labellum and spur among the analyzed taxa.