A gametophyte is a stage in the life cycle of plants and some algae that produces gametes (sex cells) through mitosis. In the plant life cycle, the gametophyte is typically haploid, meaning it has a single set of chromosomes. It develops from spores and is responsible for generating male and female gametes, which can then fuse to form a diploid zygote, leading to the next generation's sporophyte stage. In non-vascular plants like mosses, the gametophyte is the dominant stage, while in vascular plants, it is usually reduced and dependent on the sporophyte.