The life cycle of bryophytes, which include mosses and liverworts, is characterized by a dominant gametophyte stage. The gametophyte is the primary structure we recognize in these plants, responsible for producing gametes. In bryophytes, water is essential for the movement of sperm to the egg, highlighting the importance of a moist environment for reproduction.

Gametangia are specialized organs where gametes are produced, and they are found on structures called gametophores. There are two types of gametangia: archegonia, which are female and produce egg cells, and antheridia, which are male and produce sperm. Fertilization occurs when sperm from the antheridia swim to the egg within the archegonia, necessitating water for this process.

Bryophytes can be classified as monoecious or dioecious. Monoecious plants have both male and female gametangia on the same gametophyte, while dioecious plants have separate male and female gametophytes. Most mosses are dioecious, meaning that male and female structures are found on different plants.

In terms of structure, bryophytes are nonvascular plants, which means they lack vascular tissues such as xylem and phloem. Consequently, their leaves and roots are not true leaves and roots; instead, they have nonvascular leaves and structures called rhizoids that function similarly to roots but do not contain vascular tissue.

The sporophyte generation in bryophytes is typically small and less conspicuous than the gametophyte. The sporophyte consists of several key parts: the foot, which anchors it to the gametophyte and absorbs nutrients; the seta, which acts as a stalk to transport nutrients; and the capsule, which contains the sporangium where spores are produced. Spores are released from the capsule and can germinate to form a new gametophyte.

Initially, the spore develops into a structure called the protonema, which is a chain of cells that eventually grows into the mature gametophyte. This process illustrates the life cycle of bryophytes, emphasizing the transition from spore to gametophyte and the critical roles of both the gametophyte and sporophyte stages in their reproduction.