this study had not included the widely but disjunctly distributed tropical species thalassodendron ciliatum to confirm whether the two thalassodendron species have a similar chromosome number and chromosome mophology.thalassodendron pachyrhizum currently is restricted to temperate south western and may well be present as a relic of a wider distribution. the finding of a fossil species,thalassodendron auricula from indicates that this genus has a much wider distribution than during the present time.