Flora or plant life refers to the plant species of a particular region or the systematic description of their entirety. In a more general sense, the flora also includes autotrophic organisms. A flora kingdom is an area with an independent vegetation character and an independent evolutionary history (phylogenesis) of the local flora. It also houses plant species and higher plant taxa that are not found in any other area. Related species represent a floral element, which can refer to an entire floral kingdom or only a sub-area. A floral zone is a vegetation zone. The term bacterial flora is still commonly used because bacteria were previously assigned to plant systematics. It refers to the totality of all bacteria in a particular habitat.