Britannica Sources used in this answer

How does alternation of generations work in bryophytes?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Thick green bryophyte moss covers the trunks of three oak trees in a forest, with fallen leaves on the ground. — bryophyte Bryophyte moss growing on oak trees.

The life cycle of bryophytes involves an alternation of generations between two distinct phases: the haploid gametophyte and the diploid sporophyte.12

Gametophyte Generation: This is the dominant, long-lived, and photosynthetic phase. It develops from a germinating spore into a protonema and eventually into the mature gametophyte, which produces male (antheridia) and female (archegonia) sex organs.231
Fertilization: Sperm released from the antheridia swim through water to reach the egg within the archegonium. Their union creates a diploid [zygote].1
Sporophyte Generation: The zygote undergoes mitosis to form an embryonic sporophyte, which remains physically attached to and nutritionally dependent on the gametophyte. The mature sporophyte produces spores within a sporangium.13

Once released, these spores disperse to germinate and begin the cycle anew, establishing the gametophyte as the conspicuous, independent generation in bryophytes.13