Explanation:
Moss reproduces in two ways: sexually and asexually.
Moss sexually reproduces by transmitting sperm (in the presence of water) from the male plant to the female. The zygote forms a stalk (called seta) which hold spores in a small pod at its top. These spores are released when the pod is dried and blown by the wind or carriers to new locations, budding as ‘protonema’ in damp areas.
Moss reproduces asexually (also called vegetative reproduction) when parts of the plant break off and form new plants with identical genetic information.
How does moss reproduce sexually?
Moss plants (known as gametophytes) form male and female structures either on the same plant or, more likely, on different plants.
The male structures (at the top of the plant stem) are known as antheridia. The antheridium (singular) produces the sperm cells. The antheridium can form a ‘splash cup’ or ‘splash containers’ with more specialised leaves forming a rosette.
The female structure are known as archegonia (singular – archegonium) which produces the egg cells and is where the spore stem forms.
In many moss plants the male and female parts can only be seen with a microscope.
How are the plants fertilised?
Moss reproduction through rain
Fertilisation requires water
Water falling on the male plant releases the sperm cells (who swim using threadlike tails) and they are carried on splashing water droplets to neighbouring female plants. Depending on the type of plant, the water droplets can ‘splash’ between 50cm to over 2m away.
Chemical attraction ensures the sperm cells find the egg within the female archegonia. The fertilisation produces the ‘sporophyte’.
New Research on ‘Mini-beast’ fertilisation:
Scientists have discovered that microscopic mini beasts – such as ‘water bears’ are also responsible for the transport of sperm cells from male to female plants.
The ‘Sporophyte’ stage
Once the egg is fertilised, the zygote forms an embryo which grows from the female plant and forms the ‘sporophyte’ (or spore stem) which consists of a foot, stalk and capsule.
Moss Sporophyte
The foot connects the spore stem to the main plant – providing access to food and water.
The seta is the stalk that raises the pod above the plant.
The capsule is a small pod that contains the spores. Inside the capsule can be anywhere from 4 to over a million spores depending on the species of moss.
On the front of the pod capsule are a set of ‘teeth’ called the ‘peristome‘ that controls the release of the spores.
Peristome or 'teeth' on the pod capsule
The front of the capsule has a set of teeth closed together.
When the conditions are dry, the peristome opens, releasing the spores.
