Abstract: Using the common (slice-making) method, the chromosome numbers and karyotypes of three Stipa species from Inner-Mongolia steppe were studied. The chromosome numbers of the three species were found to be 2n=2x=44(2A type). In all species, metacentric chromosomes were the most common (mean value 62.1%), followed by sub-metacentrics (mean value 28.9%), and subtelocentrics were rare (mean value 9.0%). The fifth chromosome had a satellite in the three species. These results indicated that their genome structure and origin were the same. The index of asymmetry of the chromosomes decreased as the habitats became drier from the east to the west, which might be the consequence of adaptation of the three species.

Key words: Stipa baicalensis, S.grandis, S.krylovii, chromosome, karyotype