(N/A) Archegonium is the female sex organ that produces the female gamete or egg. It is present in the life cycles of bryophytes,pteridophytes,and gymnosperms.
Life cycle of a fern (pteridophyte):
The main plant body of a fern is a sporophyte,which is diploid $(2n)$. The sporophyte bears sporangia on the underside of its mature leaves. Inside the sporangia,spore mother cells undergo meiosis to produce haploid $(n)$ spores. Upon maturation,these spores are released and germinate to form a small,heart-shaped,photosynthetic,free-living gametophyte called a prothallus.
The prothallus bears both male sex organs (antheridia) and female sex organs (archegonia). The antheridia produce motile sperms that require water to swim and reach the archegonia,which contain the egg. Fertilization results in the formation of a diploid zygote. The zygote develops into an embryo,which eventually grows into a new sporophyte plant,completing the life cycle.