Moss are small, non-vascular flowerless plant species found growing in shady and damp areas. These plant species lack vascular tissues and do not produce flowers and seeds; instead, they reproduce through spores.
In the taxonomic hierarchy, moss belongs to the kingdom Plantae and division Bryophyta.
Mosses are the largest group of Bryophyta with around 1400 species. Funaria, Polytrichum, Sphagnum and Hypnum are examples of mosses.
Life Cycle of a Moss Plant
The life cycle of mosses alternates between the haploid gametophyte and the diploid sporophyte, called alternation of generation.
The female and male gametophyte produce haploid gametes, which fuse to form a zygote and give rise to the diploid sporophyte. The diploid sporophyte then produces haploid spores, germinating to the haploid gametophyte.
In structure, the gametophyte is distinguished into protonema and leafy stage, forming the male and female sex organs at their tips.
The female sex organs are known as archegonia. It functions by producing the ovum or female gamete and is protected by perichaetium modified leaves. The archegonia resemble the shape of a bottle container.
The male sex organ is known as antheridia. The antheridia are tiny, stalked and resemble a club-shaped structure. It functions by producing male gametes and is protected by modified leaves known as perigonium. The antheridium mature to release antherozoids, which are biflagellate in structure. They swim in the water and fertilise with the egg of the archegonium.
The formation of the diploid zygote leads to the second life phase of mosses, the sporophyte.
The archegonium divides to form calyptra, which acts as a protective structure for the capsule in the sporophyte.
The diploid zygote develops into a diploid sporophyte.
A sporophyte consists of a foot-long stalk called a seta, a capsule capped by the operculum.
This sporophyte remains attached to the gametophyte, which is similar to a parasite and is dependent on food and water, which divides by mitosis.
The capsule contains spore-producing cells which undergo meiosis to form haploid spores.
The capsule has teeth-like structures called peristomes, which prevent spores from falling off in wet conditions.
When the conditions are favourable, the spores are ready to be dispersed, the operculum and peristome fall off, and the spores are scattered in the environment.
The spores falling on a wet, damp ground germinate to form protonema- a threadlike, filamentous structure.
Protonema acts as a transitional structure, which later develops into a gametophyte.
Hence, this completes the life cycle of a moss plant.
Note: Mosses sometimes divide asexually. When a leaf or stem breaks off from the plant, they become individual parents and divide asexually to form new plants.
Explore More: Characteristics of Moss
This was a brief introduction to the life cycle of a moss plant.
To know more about moss plants, their physical characteristics, classification, life cycles and important questions on the life cycle of a moss plant, keep visiting our website, at BYJU’S Biology.
Frequently Asked Questions on Life Cycle of a Moss Plant
How many life cycle stages do moss plants have?
The lifecycle of a moss comprises two stages – The protonema stage and the leafy stage.
List out the uses of moss plants.
The moss plant is mainly valuable for:
- It is used as an ornamental plant.
- It is also used in various creative ways for gardening and decoration.
- Peat, the collected layers of moss, is used as a fuel.
- In old times moss plant was used as a bandage due to its water-absorbing capacity, and it was also used as a fire extinguisher.
Why can mosses not complete their life cycle in a dry environment?
Moss plants are dependent on water for sexual reproduction.
For a moss plant to complete their life cycle, they require water and here water acts as a medium for flagellated sperm to reach the egg and undergo fertilization.
Hence, mosses cannot complete their life cycle in a dry environment.