From which stage does a prothallus develop in ferns?

A prothallus develops from the gametophyte stage in ferns, which is crucial for the life cycle of these plants. In ferns, the life cycle alternates between two distinct phases: the sporophyte and the gametophyte. The sporophyte is the dominant, leafy stage that we typically recognize as a fern. It produces spores through meiosis in structures called sporangia, usually found on the undersides of fronds.

These spores are haploid and, when they germinate, they give rise to the gametophyte generation, specifically the prothallus. The prothallus is a small, heart-shaped structure that is also haploid and serves as the site for gamete production. Male antheridia and female archegonia develop on the prothallus, allowing for fertilization and the eventual formation of new sporophytes from the diploid zygote.

This life cycle is characteristic of non-flowering plants like ferns, illustrating the importance of the gametophyte stage in developing the prothallus, which is integral to their reproduction.