Abstract: Based on the information about the distribution of seed plant flora inlarge scale, and through statistical analysis, the reality of Tanaka Line’s existence and its biogeographical significance were examined. The Tanaka Line had significance in the strict limitation on the geographical distribution of SinoJapan flora, East Asia flora, and Tropical Asia flora in Yunnan, but less significance on the distribution of SinoHimalayan flora. The authors first found that the distribution of China’s endemic flora in Yunnan was possibly limited by the Tanaka Line. It was observed that the Tanaka Line did not shape the overall spatial patterns of seed plant flora in Yunnan. The Tanaka Line and its bio-geographical significance needed further exploration.

Key words: Tree roots, Senescence, Environmental factors