These plants are differentiated from the "lower" plants such as the mosses, liverworts, hornworts and green algae in two particularly important ways. In non-vascular plants, the principal generation is the gametophyte generation, which is haploid, or has one set of chromosomes per cell. In vascular plants, the principal generation is the sporophyte generation, which is diploid, or has two sets of chromosomes per cell. See also alternation of generations.
The other critical difference is that vascular plants have water-carrying structures, termed tracheids, in their tissues, enabling the plants to evolve larger and more elaborate structures, while non-vascular plants lack these.
