Included here is Guangxi, Guizhou and northern parts of the Yunnan region. In topographical terms it comprises the Tata Shan Mountains, the Szechwan Basin, part of the Kweichow Plateau and southern part of the Great Chinese Plain. Along an east-west axis, it extends the entire length of the Yangtze River.
Of the endemic and near endemic vascular plants so far recorded there are about 300 species in 187 genera and 81 families. There are 28 endemic genera (marked red) and 4 endemic families (marked purple).
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