The Patagonian flora is mainly xerophytic in contrast to the hydrophytic Magellanic flora which borders it on the west. It is a complex of elements, each of which has originated from a different geographical region. The most unusual and peculiar endemics of Patagonia, for the most part plants of swales, have their closest relationships with the Magellanic flora. Most of the Patagonian species that belong to cosmopolitan genera are apparently derived from the pampus flora to the north. The largest part of the flora has its immediate affinities with the mountain flora of central Chile. The Patagonian species with a broad hiatus in range, usually halophytes, are related to elements of the desert flora of southwestern North America. To these groups may now be added the recently introduced weed flora which is largely from Europe.