Abstract: A Taxodiaceae family is with 10 genera 16 species,including 5 monospecific genera(Metasequoia, Glyptostrobus,Sequoiadendron, Sequoia and Sciadopitys), and 5 oligospecific genera(Cunninghaimia, Tawania, Cryptomeria,Taxodium and Athrotaxis), each accounting for 50%. Taxodiaceae is distributed in north temperate regions, mostly in East Asia and North America, and only a genus Athrotaxisis in Australia Tasmania. Plants and habitat are an interdependent entity. Destruction and alteration of habitatis a serious problem for the distribution of specific genera of Taxodiaceae family. Monospecific genera mostly are relict species(living fossil), but there is only fossil in Europe due to destruction in the quaternary glacial period. Today, there are only 2 monospecific genera of Sequoiadendron and Sequoia due to the volcanoin a small area of California, US.

Key words: Taxodiaceae, monopecific genus, oligospecific genus, fossil, relict specific