Morphological diversity and phenotypic characterization of Styrax spp: Implications for conservation and breeding strategies

Abstract The lack of knowledge about phenotypic variation in Styrax spp. is a major constraint to efforts aimed at improving its resin yield, adaptability, and sustainable utilization. This study assessed the morphological diversity of Styrax spp. populations collected from both Humbang Hasundutan and Tapanuli Utara Regencies, North Sumatra, Indonesia, using correlation analysis, Principal Component Analysis (PCA), and Agglomerative Hierarchical Clustering (AHC). Field exploration was conducted across different elevations and habitats to collect 57 accessions, which were characterized based on 13 morphological traits. Correlation analysis revealed strong positive associations among leaf cluster density, seed colour, and resin characteristics, while negative correlations were observed between crown density and resin aroma, and between time of defoliation and bark texture, indicating trade-offs between vegetative traits and resin quality. PCA explained 77.28% of total phenotypic variation, with crown density, leaf cluster density, and resin colour as major contributors, while AHC grouped the accessions into three distinct phenotypic clusters reflecting ecological adaptation and resin productivity. The integration of morphological and resin traits provides a practical framework for identifying representative accessions and understanding phenotypic structure within Styrax populations. Although this study is based on morphological characterization, the observed patterns may reflect underlying biological variation and provide a useful baseline for conservation planning and preliminary selection strategies. Future studies integrating molecular approaches are required to validate the genetic basis of the observed variation. These findings contribute to the development of informed strategies for sustainable benzoin production and conservation of Styrax resources.