In the plant kingdom one of the major characteristics is the concept of alternation of generation.
Alternation of generations refers to the two main phases in the life history of plants.
The two phases are sporophyte and gametophytes. In the gametophytes stage, the plant is producing gametes which are haploid. The species in this group are non-vascular. They can't conduct water because they have no roots. They take in their water thru the roots and the stems.