Hybridization and diversity of the genus Vandenboschia in Korea insights from morphological, cytological, and genotype analyses.

The genus Vandenboschia exhibits significant diversity, driven by complex hybridization events and varying ploidy levels in the natural habitats of Korea, leads to misidentifications that obscure its true distribution and classification. To address this issue, the present study employed morphological, cytological, and genotype analyses to clarify the taxonomical circumscription and distribution patterns of the Vandenboschia radicans complex in Korea. The V. radicans complex in the genus refers to V. radicans and its closely related species and exhibits significant morphological variation, making classification challenging. Previous molecular studies have revealed that it consists of several non-hybrid and hybrid species among them. Through the present study, comprehensive sampling from Jeju and Ulleung Islands identified five distinct taxa from the V. radicans complex: two non-hybrid species (Vandenboschia kalamocarpa and Vandenboschia nipponica), and three hybrids (Vandenboschia × stenosiphon, Vandenboschia × quelpaertensis, and Vandenboschia kalamocarpa × Vandenboschia nipponica × Vandenboschia striata). Notably, hybrids exhibited broader geographic distributions compared to non-hybrid species, which were confined to specific microhabitats. While overlapping morphological traits among the species complicate identification without genetic analysis, rhizome diameter and the width-to-length ratio of the involucre can serve as key morphological traits for distinguishing members of the Vandenboschia radicans complex in Korea. Additionally, cleaved amplified polymorphic sequence (CAPS) markers and cloning techniques were employed for species identification, particularly when morphological traits were inconclusive. These findings highlight the need to integrate genetic tools with traditional taxonomic methods to resolve complex species relationships within Vandenboschia in Korea and emphasize the importance of conservation efforts for geographically restricted and genetically distinct populations.