These have well-develop roots and rigid stems. They are largely wet-habitat organism, and have flagellated sperm. Seeds are important for two reasons. Do not have flagellated sperm. Direct union of these haploid gametes leads to new diploid indivdual.
Plants appear to have inherited the alternation of generations from the multicellular green algae.
Review of the alternation of generations in mosses, ferns, gymnosperms and angiosperms. In mosses, the gametophyte is dominant. In ferns, the sporophyte is dominant. The gametophytic resembles an isolated heart-shaped leaf. There is a clear distinction between male and female gametophytes.