Chromosome numbers and karyotypes of some Australian grass species

The diploid chromosome number in root tip cells in Iseilema vaginjorum, I. membranaceum and Pseudoiseilema australiansis was found to be 2n=18. The chromosome number in P. australiansis and I. membranaceum are new reports. While the karyotypes in these three species are also reported here for the first time. The karyotypic studies in all the three species indicated that majority of the chromosomes had submedium and having very less difference in their total chromatin length. However, the three species are found to be distinct in regards to position of the sat chromosomes. The assymetrical karyotype in all these species indicated that they are in the advancing stage of evolution. The idiograms of all the three species indicated that except, the minor differnces in the position of sat pairs, they are very allied to each other and seem to have been originated from common ancestor.