societies form a long-term relationship with plant species, and create conditions for their growth. Recent research points out that human dispersers differ from animal dispersers by having a much higher mobility, based on the technical means of human transport. On the one hand, dispersal by humans also acts on smaller, regional scales and drives the dynamics of existing biological populations. On the other hand, dispersal by humans may act on large geographical scales and lead to the spread of invasive species. Humans may disperse seeds by many various means and some surprisingly high distances have been repeatedly measured. Examples are: dispersal on human clothes (up to 250 m), on shoes (up to 5 km), or by cars (regularly ~ 250 m, singles cases > 100 km). Seed dispersal by cars can be a form of unintentional transport of seeds by humans, which can reach far distances, greater than other conventional methods of dispersal. Cars that carry soil are able to contain viable seeds, a study by Dunmail J. Hodkinson and Ken Thompson found that the most common seeds that were carried by vehicle were broadleaf plantain (Plantago major), Annual meadow grass (Poa annua), rough meadow grass (Poa trivialis), stinging nettle (Urtica dioica) and wild chamomile (Matricaria discoidea). Deliberate seed dispersal also occurs as seed bombing. This has risks, as unsuitable provenance may introduce genetically unsuitable plants to new environments. Consequences Seed dispersal has many consequences for the ecology and evolution of plants. Dispersal is necessary for species migrations, and in recent times dispersal ability is an important factor in whether or not a species transported to a new habitat by humans will become an invasive species. Dispersal is also predicted to play a major role in the origin and maintenance of species diversity. For example, myrmecochory increased the rate of diversification more than twofold in plant groups in which it has evolved because myrmecochorous lineages contain more than twice as many species as their non-myrmecochorous sister groups. Dispersal of seeds away from the parent organism has a central role in two major theories for how biodiversity is maintained in natural ecosystems, the Janzen-Connell hypothesis and recruitment limitation. Seed dispersal is essential in allowing forest migration of flowering plants. It can be influenced by the production of different fruit morphs in plants, a phenomenon known as heterocarpy. These fruit morphs are different in size and shape and have different dispersal ranges,