Karyological studies of four species of Lady’s Slipper Orchids (Paphiopedilum) collected in the Bogor Botanical Garden, Indonesia

Paphiopedilum is one of the most widely grown and hybridized of all orchid genera due to its distinctive flower morphology. This genus consists of 139 accepted species and is native to southern China to tropical Asia. Karyological studies on the genus Paphiopedilum have been reported by many cytologists in different countries. However, many Indonesian members of Paphiopedilum have remained comparatively limited in investigated cytologically. This study aimed to analyze karyological characters of four species of Paphiopedilum collected in the Bogor Botanical Garden, Indonesia, namely P. armeniacum, P. hirsutissimum, P. primulinum, and P. superbiens. Karyological studies were conducted by root tips squash method. The results showed that four species of Paphiopedilum have a basic chromosome number of x = 15. They are diploid with 2n=30, instead of the common diploid chromosome number of Paphiopedilum (2n = 26). Paphiopedilum hirsutissimum and P. primulinum possess 16 m + 14 sm chromosome formulae. Whereas Paphiopedilum armeniacum and P. superbiens revealed 16 m + 14 sm and 18 m + 12 sm chromosome formulae, respectively.A Robertsonian change in chromosome number generated by the fission of chromosomes would best explain the origin of the new diploid chromosome number and karyotypes of these species.