The charophyceans Chara and haploid organisms. There is no sporophyte generation, though these algae do retain and seem to nourish zygotes on the parental bodies, as do the gametophytes of land plants. The main difference is that the zygote of a charophycean undergoes meiosis to produce haploid spores, while the zygote of a plant undergoes mitosis to produce a multicellular sporophyte, which in turn produces haploid spores by meiosis. Thus, a reasonable hypothesis for the origin of plant sporophytes is that genetic change (mutations) in an ancestral charophycean caused a delay in meiosis until one or more mitotic divisions of the zygote had occurred.