Abstract: In this paper, we analysed in detail both hepatic flora and moss flora of China and North America to have a better understanding of the bryological relationships between these two continents. The results show that the similarity coefficient of the bryophytes between China and North America is very high (up to 88.03%) at the family level, but very low (only 18.88%) at the species level. Although the separation of the two ancient continents started in the late Cretaceous, the bryophytes between China and North America with respect to the composition of families and genera are still close. Nevertheless both continents have had their own endemic genera of liverworts and mosses. There are five East Asiatic endemic genera of liverworts and 22 East Asiatic endemic genera of mosses in China, while there are four liverwort genera and five moss genera endemic to North America. It is noteworthy that the bryological relationships between eastern North America and China show a quite different pattern from those between western North America and China with respect to the families, genera and species. The sexuality of plants and the size of spores of liverworts and mosses may not be the main factors that have influenced the distribution of the bryophytes in China and North America, although they are of some importance for the distribution of bryophytes. Various information concerning the bryological relationships between China and North America (including the similarity coefficients of the bryophytes of China and North America at different levels, their endemic genera, the sibling species of the two continents, the geological history and physical geograhical conditions of China and North America, and the biological characters of bryophytes) has been analysed. It is considered that there exist close bryological relationships between China and North America, although in these two separated continents some local and endemic genera had been formed after the Cretaceous. Both bryofloras have been influenced by those of their neighbouring regions, and the Bering Strait may not be a natural barrier to prevent the bryological exchange between China and North America. In summary, the present relationships of the bryofloras between China and North America have been formed not under the influence of one simple facter or event but under a compre-hensive influence of many factors or events during the geological history.

Key words: Bryoflora, Floristic relationship, China, North America