Floral and Vegetative Micromorphology of Selected Species of Anoectochilus (Orchidaceae): Insights into Trichome Diversity and Peloria

The genus Anoectochilus (Orchidaceae) is characterized by considerable floral diversity, yet its micromorphology remains poorly understood. This study aimed to investigate the distribution and morphology of micromorphological structures in selected representatives of the genus, with particular emphasis on the putatively peloric species Anoectochilus papuanus. The study was designed as a preliminary qualitative survey, with each species represented by a single specimen. Flowers of A. papuanus, A. formosanus, and A. regalis, as well as leaves of A. papuanus and A. formosanus and the inflorescence rachis of A. papuanus, were examined using scanning electron microscopy. Trichomes, stomata, and papillae were documented on floral organs, ovaries, leaves, and the inflorescence rachis. Three principal trichome types were distinguished: oblate, pyriform, and conical. Anoectochilus papuanus exhibited the greatest observed trichome diversity, whereas only oblate trichomes were observed in the available material of A. regalis, although preservation-related deterioration prevented its comprehensive examination. Stomata were observed on floral organs and leaves, with actinocytic, desmocytic, and pericytic types recorded. Papillae occurred on different floral structures and varied in their distribution among the examined species. The labellum of A. papuanus differed from the labella of the remaining species by the presence of stomata and a wrinkled epidermis, resembling the petal surfaces. These observations are consistent with previous interpretations of A. papuanus as a peloric form and document previously unreported micromorphological variation in Anoectochilus. However, the taxonomic and functional significance of the observed characters requires confirmation using broader sampling and quantitative analyses.