1.Diploid species ofDichanthiumare genetically isolated from each other.2.Diploid races of the more commonly tetraploid speciesD. aristatum, D. annulatumandD. caricosumcould be crossed with tetraploidD. annulatum.3.Hybrids were also produced between the strictly diploid speciesD. panchganienseand tetraploidD. annulatum.4.Chromosome homology appeared to be absent between the basic genomes ofD. annulatumandD. panchganiense, while some degree of homology seemed to exist between the genomes of tetraploidD. annulatumand the diploid races ofD. aristatumandD. caricosum.5.Morphological data indicated that the Indian diploid speciesD. panchganienseandD. maccanniiare closely related. Similarly the Australian diploidsD. humilius, D. sericeum, D. setosumandD. superciliatumform a morphologically related group.