抄録
Cytological studies in two species of Epipogium, myco-heterotrophic orchids, were carried out. Epipogium roseum had the chromosome number of 2n=ca.70, 2n=35II and n=35, that was different from the previous count of 2n=68 (Singh 1983). The chromosome complement at resting stage showed the complex chromocenter type, and the metaphase II chromosomes in meiosis showed a gradual decrease in chromosome length from 1.7-0.7μm. Epipogium aphyllum had the chromosome number of 2n=72, 2n=36II and n=36, that was different from the previous counts of n=34 (Francini 1930, Afzelius 1954) and 2n=68 (Gurzenkov 1973, Uhrikova and Majovsky 1980). The chromosome complement at resting stage showed the complex chromocenter type and the metaphase II chromosomes in meiosis showed a bimodal karyotype in length consisted of three large chromosomes varied from 6.5-4.2μm and 33 small chromosomes varied from 2.1-1.4μm. Compared with the karyotype of E. japonicum (2n=78) reported by the author (2008), three species of Epipogium were different in chromosome number and length and karyotypes at resting stage and metaphase chromosomes from each other. Though, if it was thought that the one large chromosome of E. aphyllum was derived from the fusion of two small chromosomes of E. japonicum, the chromosome complements of both species were more closely allied than that of E. roseum.
