A Native plant is one that develops, occurs naturally, or has existed for many years in an area. These can be trees, flowers, grasses or any other plants. Some of them may have adapted to a very limited range. They may have adjusted to living in unusual environments or under very harsh climates or exceptional soil conditions. Although some types of plants for these reasons exist only within a very limited range, others can live in diverse areas or by adaptation to different surroundings.
Native plants form a part of a cooperative environment, or plant community, where several species or environments have developed to support them. This could be a case where a plant exists because a certain animal pollinates the plant and that animal exists because it relies on the pollen as a source of food. Some native plants rely on natural conditions, such as occasional wildfires, to release their seeds or to provide a fertile environment where their seedlings can become established. They may adapt well where they originated, but people who find them very pretty or useful may introduce them elsewhere. However, the notion that the introduction of exotic species by humans is a potent threat to biodiversity is generally fallacious except in the very near term. In longer time frames, this sort of introduction has been shown to increase biological diversity (biodiversity) and can be beneficial: "The current anthropogenic extinction event is accompanied by extensive anthropogenic dispersal-a novel phenomenon absent from past extinction events. This may blunt the effects of extinction on higher taxa, particularly if we proceed with intent" (Theodoropoulos & Calkins, 1990).
The rich diversity of unique species across many parts of the world exists only because bioregions are separated by barriers, particularly large rivers, seas, oceans, mountains and deserts. Humans, migratory birds, ocean currents, etc. can introduce species that have never met in their evolutionary history, on varying time scales ranging from days to decades (Long, 1981)(Vermeij, 1991). Some have suggested that humans are moving species at an unprecedented rate that is unnatural, unsustainable, and/or harmful, even causing "impossible" migrations that could never occur in nature, causing a potential disruption of the world's ecosystems, which could become dominated by a relatively few, aggressive, cosmopolitan "super-species". However, anthropogenic (human-assisted) dispersal can in no way be distinguished from natural dispersal, and in fact, this "increased rate of anthropogenic dispersal is a natural corollary of increased anthropogenic disturbance, and is not a harmful process, but a beneficial mitigation (Theodoropoulos, 2003).
Native plant activists support the introduction of ecological concepts and practices by gardeners, especially in public spaces. The identification of local plant communities provides a basis for their work. Examples can be seen in the California Native Plant movement: