In mosses, the alternation of asexual and sexual generations is clearly expressed.
Asexual reproduction occurs through spores (1). A thin green thread is formed from the germinated spore – a pre-growth (2-3), which looks like a thin green branching thread. On this thread buds (4) are formed, from which male (7) or female (8) specimens of moss then grow.
We will consider sexual reproduction using the example of cuckoo flax moss. The cuckoo flax has female and male plants. Male gametes – sperm cells – develop on male plants, female gametes – eggs – are formed on female plants. When it rains or during floods, sperm cells float in the water to the eggs (9).
When gametes merge, a zygote is formed, which, without leaving the female organ, begins to divide. From the zygote on a female plant, a cap-covered capsule on a leg – sporangium (10) develops. Disputes form in the sporangium. In dry weather, the cap is shed, the spores disperse (1) and germinate into pre-growths (2–3), giving rise to new male (7) and female (8) cuckoo flax plants.
Thus, in cuckoo flax moss, a change of generations occurs during its life – asexual and sexual (sporophyte and gametophyte). Gametophyte (sexual generation) is represented by leafy shoot. Sporophyte (asexual generation) is a box with a long stem. Plants of the asexual generation live off the plants of the sexual generation.
During vegetative propagation, many mosses develop cushion-like sods and cover the moist soil with a continuous carpet.