Alternation of generation is what happens in the asexual reproduction of vascular plants in their gametes, as haploid cells that came from their gametes, spores fertilizes another plant becomes a diploid cell in the process.
In terms of vascular plants, they help maintain the water cycle. The property of these plants enables them to carry out this function is their well-developed vascular system. These type of plants are more evolved and developed than nonvascular plants because of its specialized characteristics like xylem, which is a tissue that is responsible for its framework and not only that, it is also has a greater mechanism for water transference. Another is phloem, which is responsible for food conduction.