MAIN BODY FORM. “Plants alternate between two generations—one haploid and the other diploid. In flowering plants, the main plant body forms the “sporophytic” generation, within which highly reduced male and female “gametophyic” generations develop.” There are exceptions such as bryophytes (mosses, liverworts, and hornworts), where the gametophyte is the main body form, or ferns where the sporophyte is the main form.
http://www.sciencedirect.com/science/article/pii/S1534580713000427