Integrating traditional and geometric morphometrics to assess floral morphological variation and taxonomic resolution in Dactylicapnos (Papaveraceae)

Despite the acknowledged importance of floral morphology for distinguishing species in Dactylicapnos, the patterns of floral variation and their taxonomic resolution remain poorly understood due to the absence of a comprehensive morphometric analysis. To address this gap and to investigate floral divergence across all 15 recognized species, we integrated traditional morphometric methods (TMMs) and geometric morphometric methods (GMMs). Five floral traits and 22 landmarks were quantified with multivariate analyses. Significant morphological divergence was observed between annual (D. section Minicalcara) and perennial species, with the former characterized by elongated, lacerate–dentate sepals and slender corollas with reduced outer petal spread. Principal component analysis pinpointed corolla dimensions and sepal features as primary sources of floral variation. Transformation grids revealed floral expansion trends with sepal shortening from annual to perennial species. In addition, methodological comparisons showed that TMMs outperformed GMMs in species discrimination, achieving higher accuracy in both canonical variates and discriminant analyses and with superior resolution in principal component and cluster analyses. These findings highlight the importance of TMMs in morphological discrimination within Dactylicapnos, although GMMs provide complementary insights into shape allometry. Future research will integrate morphometric approaches with molecular data to enhance taxonomic accuracy in this challenging genus.