Round and Round it Goes: Life Cycle of a Plant

Gametophyte: The multiple cellular haploid form that produces haploid gametes by mitosis. These gametes unite and develop in sporophytes.

Sporophyte: The multicellular diploid form that results from the union of gametes. It helps produce haploid spores by meiosis that develop into gametes. 

The life cycle of a plant: it begins when the gametophyte produces haploid gametes by mitosis. Then, two gametes unite to form a diploid zygote by fertilization. The zygote develops into a multicellular diploid sporophyte which then produces haploid spores through meiosis. The spores develop into multicellular haploid gametophytes. This is how land plants undergo sexual reproduction.