Vascular Plant Families & Genera: Interactive map
How to use the map
Click on a region to access the popup boxes which show various charts and statistics for that region. The top bar chart shows the numbers of plant genera, families, endemic* genera and endemic families that each region holds, compared with the maximums for all the regions (there are 52 regions in total). The genera and family pie charts show the number of genera and families in that region, compared with the world total.
*A plant (or plant group) is said to be endemic to a particular region when it occurs naturally only in that region and nowhere else.
Western South America has the greatest number of plant genera, because of the large number of different habitats it covers (desert, coastal, rain forest, high and low altitude). It is more diverse than Brazil which is larger but has a smaller range of habitats and especially mountains.
China contains the highest number of plant families, due to its size and the large number of habitats contained within it. If you were to take the different sizes of the regions into account, it is actually the Southwestern Pacific which has the greatest number of families, although this region is mostly small islands so it appears to be much less diverse than it really is.
All the areas which have very large numbers of families or genera include both tropical areas and colder, more temperate areas, and they contain a large range of habitats with elements of both of these distinct floras. This is even true of Western South America, where plants adapted to colder habitats are found at high elevations in the Andes.
The region with the fewest genera of plants is St. Helena and Ascension Island in the Atlantic Ocean, with only 55. These islands are both very small and very isolated, from each other and from surrounding continents, so very few plants have managed to disperse to these islands.
How we did it
For each genus of flowering plants, distributions were compiled principally from the specimens held in Kew's Herbarium. In addition, standard reference floras and checklists for each region of the world (as far as possible) were consulted for doubtful distribution records (such as only one or a few specimens of any genus from a particular region, or doubtfully identified specimens). Many hundreds of individual articles were also consulted, and whether or not a genus was native, doubtfully native, doubtfully present or introduced was noted. Only presence has been recorded; regions from which a genus is absent are not listed, and there is no record of abundance, extent of distribution within regions, or numbers of species either of genera or within regions.