^1-8Department of Agrotechnology, Faculty of Agriculture, Sebelas Maret University, Surakarta, Indonesia

^1-7Plant Breeding Laboratory, Agrotechnology Study Program, Faculty of Agriculture, Sebelas Maret University, Surakarta, Indonesia

^1,5,6,7 Center for Research and Development of Biotechnology and Biodiversity (P3BB), Institute for Research and Community Service (LPPM), Sebelas Maret University, Surakarta, Indonesia

Email: tatik_oc@yahoo.com

Phaius tankervilleae and Phaius amboinensis orchids are decorative orchids that have great ornamental value and are classified as endangered plants. Genetic information from the Phaius tankervilleae and Phaius amboinensis orchids will facilitate plant breeding as a basis information to obtain improvements in ornamental plant properties. The purpose of chromosome analysis is to determine the shape, number, and size of chromosomes. The research was conducted at the Cytology Laboratory of the LIPI Biology Research Center, Bogor, West Java. The results of the observations were analyzed descriptively based on the observation of the chromosome images from the photo shoot and the data on the size and shape of the chromosomes.  It is known that the Phaius tankervillae has a chromosome number of 2n=2x=44 and Phaius amboinensis has a chromosome number of 2n=2x=46. The average length of the long arm of the Phaius tankervillae chromosome was 1.25 ± 0.45 µm with the short arm of 1.13 ± 0.43 µm. The long arm length of the Phaius amboinensis orchid chromosome is 1.25 ± 0.44 µm with the short arm 1.06 ± 0.37 µm. Phaius tankervillae and Phaius amboinensis both have metacentric chromosomes meta.