Karyotypes of Paphiopedilum Species of Thailand1

Abstract

Species of the genus Paphiopedilum, commonly known as Cypripediums or Lady Slippers, are distributed south of the Himalayas along the Indo-Malayan region to the Philippines. About 9 species are known to occur in Thailand. Also a few putative natural hybrids have been recorded, but their taxonomic relationships are not clearly defined (Seidenfaden and Smitinand, 1959). The chromosomes of the Paphiopedildums are relatively favorable for cytological examinations because of their large size and strong affinity for stains. Duncan and MacLeod (1948a, 1948b, 1950) examined several species including some native species of Thailand and constructed ideograms illustrating the similarities and differences of chromosome complements. Since a comparison of karyotypes often provides an insight into species relationships and evolution the present investigation was initiated to determine whether karyotype analysis employing a slightly modified technique from that of Duncan and MacLeod might shed some light on the phylogenetic relationships of the Paphiopedilum species of Thailand.