TRACHIOFITA are vascular plants encompassed by the taxon Tracheophyta or C]Tracheobionta. They are organisms formed by plant cells, which have a life cycle in which the gametophytic and sporophytic generations alternate, being dominant, and on which there is more pressure of natural selection; its sporophytic phase is photosynthetic and independent, and has tissues and organ systems; it is organized in a CORMO whose gametophytic phase is reduced and can be from a "thallus" (body not organized in tissues or organs) in ferns and related, to a few cells protected and nourished by the sporophyte, in gymnosperms and angiosperms. Natural selection strongly directed the evolution of tracheophytes towards less dependence on environmental conditions on earth for their reproduction and dispersal, which is evident when comparing the oldest tracheophytes (Lycophyta with the more modern (flowering plants).