Morphological and phylogenetic analysis of Schisandra and Kadsura: distribution, trait variation, and hybridization potential

To enhance the research and evaluation of Schisandra and Kadsura germplasm, we investigate their geographical distribution, morphological traits, and phylogenetic relationships. We found that both genera co-occur across a broad latitudinal range (23°–50°N), with Schisandra exhibiting a wider altitudinal range (0–4500 m) than Kadsura (0–1500 m). Morphological analysis of 20 traits across 41 species (24 from Schisandra and 17 from Kadsura) revealed significant overlaps alongside key distinguishing characteristics. Principal component and orthogonal projections to latent structures discriminant analyses identified flower sexuality, gynoecium morphology, and fruit attributes as primary sources of variation, with some of the Schisandra species (e.g., S. plena, S. propinqua) clustering morphologically with Kadsura. Phylogenetic reconstructions based on ITS and matK sequences confirmed a close evolutionary relationship between the genera and suggested potential intergenus hybridization, particularly involving S. bicolor, S. propinqua, S. plena, and K. scandens. Our findings provide a foundational framework for understanding the biogeography, trait evolution, and complex phylogeny of these genera, highlighting specific species as prime candidates for future research on hybridization and conservation.