The diversity of vascular plants in Burundi is still insufficiently explored, described and understood. The objective of this article is to show the degree of botanical exploration and the spatial patterns of botanical diversity in Burundi to date.

The study is based on a data set containing virtually all plant collections, observed in herbariums, recorded in databases or cited in the literature, carried out in Burundi. All data has been compiled, cleaned, and each record georeferenced. Various distribution analyses were performed, some of which were based on a grid of 199 hexagonal cells.

The data set includes 37200 herbarium collections representing 3,860 species grouped into 1,290 genera and 216 families. The expected specific wealth is estimated at 4,869. The average number of collections per species is 8.8, but 1,149 species (27%) are sampled only once. The seven most species-rich families are Fabaceae (539 spp.), Poaceae (387), Poaceae (387), Asteraceae (298), Orchidaceae (286), Cyperaceae (272), Rubiaceae (227), and Acanthaceae (227), and Acanthaceae (227), and Acanthaceae (128), which together represent more than 50% of Burundi's vascular plant flora. The seven most important genera are Cyperus (90 spp.), Crotalaria (60), Indigofera (50), Polystachya (48), Habenaria (47), Vernonia (47), Vernonia (45), and Eragrostis (41). In terms of the number of herbarium collections, the six most important families are Poaceae (4,754 collections), Fabaceae (4,300), Asteraceae (2,226), Rubiaceae (2,191), Rubiaceae (2,191), Cyperaceae (2,191), Cyperaceae (1,730), and Lamiaceae (1,275). FrenchThe four most intensively explored areas that present the greatest diversity of known species are the Rusizi plain, the Kibira tropical forest belonging to the Albertine Rift, the Bururi and Rumonge regions in the west, and the regions of Bururi and Rumonge in the west and the Mosso depression in the east.

With a collection index of 133 collections per 100 km2, botanical exploration in Burundi can be considered relatively good. However, 28% of species are represented by only one record and around 1,000 species are potentially present but have not been collected to date. For every 100 new collections, there are an average of 6 new species recorded, which indicates that Burundi's inventory is still not complete.