floristic kingdom (noun,biogeography term, pl. floristic kingdoms) – a geographic area with a relatively uniform composition of plants (or plant-like organisms) that share a common distribution history. Floristic Kingdoms are largely a result of the development of continents through processes like continental drift. These geographic processes represent evolutionary constraints that resulted in the isolation of species from one another. Floristic kingdoms lack sharp boundaries because distribution mechanisms of different organisms vary considerably in their effectiveness to overcome geographic constraints Instead of clear cut boundaries between the kingdoms, transition zones may be recognized where species from both areas overlap. These areas are vegetation tension zones because organisms compete along these zones. widespread organisms have very successful distribution mechanisms that effectively overcome distribution limits, that, in contrast, cannot be breached by endemic organisms, i. e., species confined to limited geographic areas. Several systems of floristic provinces have been proposed, most are hierarchically organized, with the larger regions subdivided into smaller geographic units. Floristic kingdoms are similar but not identical with zoogeographic (= faunistic) kingdoms. Most frequently the following six kingdoms are distinguished: the holarctic, neotropic, palaeotropic, South African, Australian and Antarctic kingdom. The largest kingdom, the paleotropic kingdom, is often divided into three subkingdoms, each subdivided into floristic provinces. The other five kingdoms are usually directly subdivided into provinces. Almost all provinces can be further subdivided into floristic regions that are sometimes subdivided into distribution sectors. This terminology is, however, not uniform. Some classifications divide kingdoms into subkingdoms, provinces, and regions; others divide kingdoms into regions, and regions into provinces.