Yeon-Ji Lee1P, Seong-Hyeon Yong1, Da-Bin Yeom1, Ye-Rim Choi1,

Balkrishna Ghimire2, Kyung Choi1, Mi-Jin Jeong1

1Division of Forest Biodiversity, Korea National Arboretum, Pocheon, Korea;

2Faculty of Forestry, Agriculture and Forestry University, Hetauda, Nepal

Taxonomic studies of Rhododendron have largely focused on palynology, molecular phylogeny, and external morphology, whereas seed morphology and seed-coat micromorphology remain comparatively underexplored. In this study, we examined seeds of ten East Asian Rhododendron species to evaluate the taxonomic usefulness of seed morphological characters. Overall seed morphology was documented using electron micrographs, and seed-coat micromorphology was assessed based on diagnostic surface characters, including surface pattern, anticlinal wall, periclinal wall, ridge pattern, ridge density, and ridge morphology. Most species shared a broadly striate surface pattern, yet interspecific variation was evident in the configuration of anticlinal walls and ridge characters. Additionally, both basal wings and apical wings were observed in R. aureum and R. brachycarpum, while apical wings were observed in R. micranthum and R. mucronulatum. The seed size, shape, presence of appendages, and surface micromorphological characteristics can be considered for species identification within the genus. Collectively, the combination of gross seed morphology and seed-coat micromorphological characters provides practical features for species discrimination with in Rhododendron and offers foundational data for further taxonomic research, with potential relevance to restoration and seed-based species authentication studies.

This research was supported by Scientific Research Grants (KNA 1-2-41-22-1) of the Korea National Arboretum.