Moss

The majority of Bryophyta, which are tiny, nonvascular, spore-bearing plants that often grow in wet, shaded environments, are mosses. They are well-famous for the plants that coat the ground in forests and woodlands.

Mosses decompose the exposed substrate, generating nutrients for use by more complicated plants that take their place. By offering surface cover and absorbing water, they also help to minimise soil erosion. There are fossilised remains of more than 100 moss species, with the most significant species belonging to the genus Sphagnum, which produces peat.

Similar to other bryophytes, mosses present an alternation of generations, or metagenesis, which results in the production of sperm and eggs, the reproductive organs, and the dependent sporophyte spores cycle, which results in spores. The structure and specificity of sporangia are the primary ways that mosses differ from one another.

What is Moss?

Mosses are tiny, flowerless plants that belong to the Bryophyta division, alongside liverworts and hornworts. They lack xylem and phloem-like vascular systems and primarily absorb water and nutrients through their leaves. They typically grow in bunches or mats on the forest floor in wet, shaded areas. Mosses often only reach a height of 10 cm, although the unusual genus Dawsonia can reach heights of 50 cm. Mosses prefer to live in moist conditions. These specialised plants are seedless, without flowers or roots.

Characteristics of Mosses

Mosses have the following physical characteristics:

• The plant lives as a haploid gametophyte- a dominant stage and a diploid sporophyte.

• The leaves are tiny, straightforward, organised spirally, occasionally layered with just a single row of cells, and strong midribs.

• Rhizoids, a type of thread-like structure that the roots possess, aid in their ability to adhere to the substrate.

• The stems are typically free-standing, weak, and green to brown in colour.

• Due to the absence of seeds, moss reproduces through spores.

• The tall, unbranched stems of the sporophytes are short-lived. For water and nutrients, they largely rely on gametophytes.

The Life Cycle of Mosses

Moses goes through two stages in their life cycle: the haploid stage and the diploid stage. The haploid gametes produced by the male and female gametophytes combine to form a zygote, which then develops into the diploid sporophyte. The haploid spores that the diploid sporophyte produces, later on, germinate to form the haploid gametophyte. It is called the alternation of generations when such a transition occurs between gametophytes and sporophytes.

In the table below, the specific characteristics of the haploid and diploid stages are listed:

Gametophyte

The female sex organs, called archegonia, have a bottle-container-like appearance. It produces the female gamete or ovum, guarded by perichaetium-altered leaves. The male sex organ, called antheridia, is a small stalk structure that resembles a club. It generates male gametes and is guarded by altered leaves known as perigonium. Antherozoids that have a biflagellate shape are released once the antheridium reaches maturity. They move through the water while uniting with the archegonium's egg.

The second life phase of mosses - sporophyte results from the production of a diploid zygote. The sporophyte's calyptra, which is formed when the archegonium separates, serves as a protective structure for the capsule.

Sporophyte

The diploid zygote grows into a diploid sporophyte, with an operculum-capped capsule and a seta, a foot-long stalk. This sporophyte sticks to the gametophyte, which divides by mitosis and resembles a parasite that depends on food and water. Sporophyte spore-producing cells that go through meiosis to create haploid spores are present in the capsule.

Peristomes, which resemble teeth, are parts of the plant that keep spores from slipping off when wet. The operculum and peristome fall off as the spores are prepared for dispersal, and the spores are then spread across the environment. Protonema, a threadlike filament structure, is created when the spores that fall on wet, damp ground germinate.

Moss Uses

The moss plant is useful mostly for the following purposes.

• It is grown for ornamentation.

• It is also applied to gardening and decoration in a variety of inventive ways.

• The moss plant was once used as a bandage and a fire extinguisher because of its ability to absorb water.

Moss Types and Species

The Bryophyta moss group, which has about 14000 species, seems to be the largest. Examples of moss plants include Funaria, Polytrichum, Sphagnum, and Hypnum. Mosses can be classified into a few different types depending on their growth nature.

Sheet moss, which grows along the ground in carpets; Cushion moss, which forms smaller clusters like seat cushions, and Rock cap moss, which thrives on the tops of rocks.

Interesting Facts

Sometimes mosses reproduce asexually. A leaf or stem fragment that separates from the plant becomes a separate parent and divides asexually to create a new plant. Mosses can develop on rocks, fallen wood, or in places having poor quality or absence of soil in which other plants cannot grow.

Important Questions

1. What characteristics are common among mosses and ferns?

Ans: Both ferns and mosses are non-vascular, spore-producing species. Generational changes are made to them. Water is necessary for fertilising both ferns and mosses. Given that their sperms contain flagella.

2. How does moss survive in its surroundings?

Ans: The photosynthetic process is present in moss, just like it is in vascular plants. For moss to survive, it needs both moisture and light. Certain mosses take nourishment through their rhizoids, whereas others gather moisture and minerals through the surfaces of their extremely absorbent leaves.

Key Features

• Mosses are a particular kind of bryophyte, a class of non-vascular plants.

• Except for salty regions, mosses are remarkably widespread, with more than 14,000 species being identified worldwide.

• Mosses have a special reproductive cycle known as the alternation of generations that switches between the haploid gametophyte and the diploid sporophyte.