During which stage do plants produce gametes through mitosis?

Plants produce gametes through mitosis during the gametophyte stage. In the life cycle of plants, specifically in the alternation of generations, the gametophyte is the haploid phase that arises from spores produced by the sporophyte. The gametophyte generation directly produces gametes—sperm and eggs—by mitotic division. This process is crucial because it generates gametes without the need for meiosis, maintaining the haploid state of the gametes.

In contrast, the sporophyte stage is diploid and primarily involves the production of spores through meiosis, which eventually leads to the formation of the gametophyte. The protonema is the initial stage of moss development following spore germination, serving as a preliminary stage before the full gametophyte structure develops. Rhizoids are structures that help anchor the gametophyte but do not play a direct role in gamete production. Thus, the correct identification of the stage where gametes are produced via mitosis is firmly within the gametophyte phase.