抄録
Cypripedium macranthos is a polymorphic species with wide variation in vegetative traits, flower color and morphology. For the future infraspecific taxonomy of C. macranthos s. lat., I quantitatively clarified the variation of those traits in C. macranthos var. rebunense and var. macranthos on Rebun Island, Hokkaido, Japan. A quantitative analysis of flower color using the L*a*b* color system revealed distinct differences between the pale cream flowers of var. rebunense and the purplish pink flowers of var. macranthos. However, especially in the measurements of a* and b*, the flowers of var. rebunense showed wide variation (from white or pale cream to yellow, including greenish yellow). Even on Rebun Island alone, C. macranthos s. lat. showed a wide range of variation in outer morphological traits. It is not possible to clearly discriminate between var. rebunense and var. macranthos by vegetative and morphological floral traits, only in the difference in color of flowers. However, the ratio of petal length to width in var. rebunense tended to be slightly smaller than for var. macranthos. Within var. rebunense on Rebun Island, the southern Rebuntaki population showed a slight tendency toward smaller dimensions in vegetative and floral morphological traits than in the other two northern populations. Special attention should be paid to the southern part in the protection of C. macranthos var. rebunense on Rebun Island.
