Taiwan Island, which covers an area of ca. 35989 km2 and ranges from 21°45‘ to 25°56‘N and from 119°18‘ to 124°34‘ E, is the largest one in China with the highest peak about 3997 m above sea level. The flora comprises ca. 3656 species in 1201 genera, of which 29.3% of species and only four genera are endemic to Taiwan. Evaluated in this paper is the importance of the 14 larger families which together contain 50.1% of the total number of species. Among the native genera of the seed plants flora of Taiwan, 742 (61.8%) are tropical, 346 (28.8%) temperate. It is clear that tropical genera play an important role in the flora of Taiwan. According to the distributional patterns of dominant species and Chinese endemic species, the flora of Taiwan is basically subtropical in nature. This flora includes an unusually high proportion of endemic species and is of prominent subtropical nature in composition. On the basis of analysis of geographical distribution of genera and nonendemic species of seed plants, the floristic affinities between Taiwan and the mainland of China are well documented by the presence of more than 1150 genera (96.3 % of total genera) and 1140 nonendemic species (48.2% of total nonendemic species.)