Yunnan and Taiwan are of important biogeographical significance for the East Asian flora; they are at similar latitudes and have similar geography and vegetation. Comparing their floras may lead to a better understanding of the geological history, floristic variation, and evolution of East Asian floras. Previous studies have shown that both the present flora and the palynoflora of Taiwan have close affinities to those of mainland China.
Prof. ZHU Hua of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to compare both floristic composition and geographical elements of Yunnan and Taiwan. He aimed to assess the floristic similarity and variation as well as biogeographical affinities between these two regions, which may contribute to the understanding of geological history and the floristic evolution and variation of East Asia.
A total of 13,253 native seed plant species in 2140 genera and 225 families were recognized from Yunnan. A total of 3411 species in 1234 genera and 190 families were recognized from Taiwan. The total number of native seed plant species in Yunnan is more than four times the total species in Taiwan.
Although the flora of Yunnan is much more diverse than the flora of Taiwan, it is conspicuously similar in floristic composition and biogeographical elements. Yunnan and Taiwan share many of the same species-rich families in their floras.
The top 50 families ranking in species richness in Yunnan and Taiwan contribute to 78.8% and 79.0% of their total floras, respectively. Thirty-nine of the top 50 families in both Yunnan and Taiwan are shared between the two provinces. (2) The families of tropical distribution make up 52.4% and 50.5% of the total families in Yunnan and Taiwan, respectively, of which those of pantropical distribution contribute most among all geographical elements, making up 34.2% of the total families in Yunnan and 37.9% of the total families in Taiwan. The genera of tropical distribution contribute 57.3% of the flora of Yunnan and 60.9% of the flora of Taiwan. (3) The flora of Taiwan shares 96.3% of its families and 84.7% of its genera with the flora of Yunnan.
The high floristic similarities between Yunnan and Taiwan indicate their close floristic affinities, despite the distance between the provinces.