What does alternation of generations mean in the fern life cycle?

In the life cycle of a fern, alternation of generations refers to the regular cycle between two distinct phases: the asexual sporophyte generation and the sexual gametophyte generation. These phases differ in their physical structure and chromosome count.12

• Sporophyte Generation: This is the dominant, familiar fern plant consisting of roots, stems, and leaves. It is diploid, meaning its cells contain two sets of chromosomes. Through meiosis, the sporophyte produces haploid spores within specialized organs called sporangia.324
• Gametophyte Generation: When a spore germinates, it develops into a tiny, inconspicuous, heart-shaped structure known as a prothallium. This phase is haploid, containing only one set of chromosomes. The gametophyte produces gametes (sperm and eggs).3241

Following fertilization, where sperm and egg unite to form a diploid zygote, a new sporophyte develops, and the cycle begins again. In most ferns, the gametophyte is short-lived and withers once the new sporophyte is established.32