Meiosis produces spores in plants, according to Kimball's Biology Pages. Spores are the beginning of the gametophyte generation, which produces gametes via mitosis as the starting cells are already haploid.
Meiosis is a cell division process in eukaryotes that consists of two consecutive divisions: meiosis I and meiosis II. These two divisions do not have DNA synthesis or S phase. Meiosis results in four cells with half the number of chromosomes of the starting cell. When two such cells combine, a 2n zygote is created.
Meiosis and fertilization divide the life of most plants into two different phases or "generations." The gametophyte generation starts with a haploid spore produced through meiosis. All of the cells derived from the spore by mitosis are also haploid. Over time, this multicellular structure produces gametes via mitosis, and then sexual reproduction creates the diploid sporophyte generation, which begins with a zygote and has cells consisting of the diploid number of chromosomes. Some cells eventually undergo meiosis and form spores, thus beginning a new gametophyte generation.
This plant life cycle reveals that mitosis can occur in both haploid and diploid cells. Moreover, a haploid set of chromosomes is enough to control cell function in plants. In most mosses and ferns, the gametophyte generation is the major stage in their life cycle.