Interspecific Variation in Stomatal Traits among Six Korean Hosta Species

Although numerous Hosta cultivars have been developed for horticultural purposes, the growing attention to wild Hosta species under climate change highlights the need to evaluate their ornamental value and ecological adaptability. Among various morphological features, stomatal characteristics play a pivotal role in plant responses to environmental stressors. The present study investigated six Korean Hosta species (H. capitata, H. clausa, H. jonesii, H. minor, H. venusta, and H. yingeri) to establish foundational data on interspecific variation in leaf-level adaptive traits. All of the taxa exhibited an anomocytic stomatal type characterized by the absence of distinct subsidiary cells surrounding the guard cells. Despite this shared morphology, substantial differences were observed in the stomatal dimensions and frequency; H. yingeri displayed the largest guard cells (up to 1.24-fold), whereas H. clausa had the highest stomatal density (up to threefold), accompanied by the smallest size. A significant negative correlation was found between the stomatal size and density (r = –0.61^***). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed discrete groupings based on stomatal traits, with H. clausa and H. yingeri forming separate clusters. These findings provide critical baseline information for interpreting interspecific differences in habitat preferences, foliar morphologies, and adaptive strategies among Korean Hosta species.