sporofyte

Sporophyte is the diploid, multicellular phase in the alternation of generations found in plants and some algae. It develops from the fertilized egg (zygote) and grows into the body of the plant that is distinct from the haploid gametophyte. The defining feature of the sporophyte is its production of spores rather than gametes. Spores are produced by meiosis within sporangia, and these haploid spores germinate to form the gametophyte generation, which then produces gametes by mitosis. Fertilization between compatible gametes restores the diploid state and gives rise to a new sporophyte.

Across land plants, the sporophyte varies in prominence. In bryophytes (mosses, liverworts, hornworts) the sporophyte is typically small and dependent on the gametophyte for nutrition. In vascular plants—ferns, lycophytes, gymnosperms, and angiosperms—the sporophyte is the dominant and often conspicuous stage, capable of photosynthesis and independent growth. The sporophyte bears sporangia, which may be organized in sori on fern fronds, around strobili in horsetails and clubmosses, or within cones and flowers in seed plants.

In seed plants, the sporophyte produces two kinds of sporangia: microsporangia (pollen) and megasporangia (ovules). The microspores develop into male gametophytes (pollen grains) and the megaspores develop into female gametophytes within the ovule. After fertilization, the resulting zygote grows into a new sporophyte embryo within a seed (in gymnosperms and angiosperms). Thus, the sporophyte generation embodies most of the plant’s morphology in seed plants and is central to the plant’s life cycle and reproduction.