Included here is Cambodia, the southern parts of Laos, a small part of Thailand and southern Vietnam (Cochin China). In the south, it is delimited by the lowlands of the Mekong Delta, while in the northwest it is bordered by the Chuor Phnum Dangrek Range and a limb of the Kravanh Mountains.
Of the endemic and near endemic vascular plants so far recorded there are about 687 species in 326 genera and 113 families. There are 3 endemic genera (marked red) but no endemic families.
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