The grasslands of southeastern Gabon’s Plateaux Batéké are maintained by regular anthropogenic fire and are located on the northernmost extension of the Kalahari sands. Fire and substrate are important for species composition on southern areas of the Kalahari sands, but the influence of these two factors on vegetation composition has never been explored for the northern region. Through the analysis of a subset of taxa and their distributions, the floristic affinities and influence of fire and substrate are explored. Although over 50% of the flora is classified as Guineo-Congolian another 20% of the species have extended distributions into the Zambesian or Sudanian phytochoria. Forest endemics were high, grassland endemics were absent supporting the anthropogenic nature of the grasslands. Twenty per cent of the flora consists of successional species present primarily at the grassland-forest interface. Twenty four percent of grassland species were arenicolous (sand obligates), but these were also pantropical and pan African species. Pyrophytes were poorly represented. Fire and substrate do not seem to have influenced speciation like they have on the southern Kalahari sands where pyrophytic and arenicolous endemics are abundant. However, ecologically, these fire and sand specialist species are important: fire maintains the grassland which is in turn colonized and stabilized by arenicolous and pyrophytic species. The preservation of this region of Gabon as a national park is noteworthy in that it not only preserves the genetic diversity of the forest grassland mosaic, but also conserves the fire-mediated landscape located on these northernmost Kalahari sand deposits.