Mosses

Mosses are the second group of bryophytes. In their life cycle the gametophyte is the dominant, most prominent stage, and this gametophyte passes through two distinct stages.

The two gametophyte stages

• The first is the protonema stage. It grows straight from a germinating spore and takes the form of a creeping, green, branched structure that is often filamentous (thread-like).
• The second is the leafy stage. It arises as a lateral bud on the secondary protonema. This stage consists of upright, slender axes that bear leaves arranged in a spiral around them. These leafy shoots are anchored to the soil by rhizoids that are multicellular and branched. It is this leafy stage that carries the sex organs.

Vegetative reproduction

Mosses can reproduce vegetatively by fragmentation and by budding on the secondary protonema, allowing new plants to form without sexual reproduction.

Sexual reproduction and the sporophyte …