Bryophytes and its Classification

In this article, we describe the plant kingdom’s second part Bryophyta. We are explaining Bryophytes and the classification of Bryophytes. It is important to the exams point of you. This article is useful for many competitive examination like SSC, Banking, Railways etc. Bookmark this article for future reference.

Bryophyta :

Bryophyte is proposed as a morphological division containing three groups of non-vascular land plants referred to as embryophytes. liverworts, hornworts, and mosses are the three non-vascular land plants. These are tiny plants that developed in shady and damp places. They are free of vascular tissues. They reproduce via spores instead of flowers and seeds.

The structure of the plant body is thallus-like and prostrate or erect, and it is combined with the substratum by unicellular or multicellular rhizomes. Bryophytes have specialized tissues that function to move water, but they are not described as true vascular tissues because of the absence of lignin. Bryophytes are believed to have originated from charophytes and are believed to be the first true plants to evolve. The bryophyte’s primary plant body structure is haploid, generates gametes, and is thus known as a gametophyte. The male sex organ is also known as antheridium, and it is developed biflagellate antherozoids, while the female sex organ is flask-shaped and generated a single egg.

Bryophytes are known as  “amphibians of the plant kingdom” because they are terrestrial plants and amphibians in nature, that need water to complete their life cycle during sexual reproduction.

Division Of Bryophytes :

Bryophytes are divided into three categories : 
1. Hepaticopsida (Liverworts)
2. Anthocerotopsida (Hornworts)
3, Bryopsida (Mosses)

Hepaticopsida (Liverworts) :

The name Hepaticopsida originates from the word “hepatic” which means liver. Liverworts are a type of bryophyte that belongs to this group. It has approximately 900 species. The primary bryophytes are liverworts. They are mostly found in moist rocks and wet soil. because they live close to the water.

Classification Of Hepaticopsida :

Hepaticopsida is further divided into 4 categories :

1. Marchantiales (e.g. Riccia, Marchantia)
2. Sphaerocarpales (e.g. Sphaerocarpos)
3. Calobryales (e.g. Calobryum)
4. Jungermanniales (e.g. Pellia)

Marchantiales :

The Marchantiopsida are a group of liverworts that belong to the Marchantiopsidae family. Species within this range are widely distributed and can be found throughout the world, including Antarctica. Marchantia has both types of Reproduction which occur sexually and asexually. Example- Riccia, Marchantia

Sphaerocarpales :

The gametophyte in Sphaerocarpales is leafy and consists of a spindle consisting of two rows of alternately fused lobes of “leaves”. The development and structure of the sex organs as well as the structure of the sporophyte are similar to that of the merchant-like sparrowcarpos.

Calobryales:  

Calobryales are part of the bryophytes plants and are called liverworts. The leaves of the Calobryales plant are flattened and in three rows on upright shoots arising from a colorless, underground, root-like system that does not have rhizoids. Example-Calobryum.

Jungermanniales:

Jungermiales is the largest group of the class Hepaticopsida in the Bryophyta division. Jungermiales is consist of approximately 9000 species. Jungermanniales members are known as leafy liverworts. Example- Pellia

Characteristics of Hepaticopsida :

• The gametophyte plant may be thalloid or foliose.
• It is usually dichotomously branched and may be thalloid, i.e, flat or spiral in shape. 
• Rhizoids are unicellular, branched, and septate.
• The sporophyte is made up of only the capsule (in Riccia) or foot, seta, and capsule (in Marchantia). In the capsule, there is no columella.

Anthocerotopsida (Hornworts) :

Anthocerotopsida (Hornworts) is part of the class of bryophytes. There are approximately 300 species are present. It is also referred to as hornworts. It has only one order i.e. Anthocerotales such as Anthoceros, Megaceros, and Notothylas. This group of bryophytes is slightly more developed compared to Bryopsida and Hepaticopsida in a few ways. The gametophyte is extremely lobed and irregular from a broad perspective. With the exception of the initial phases of growth, the sporophyte does not rely on the gametophyte for protection or sustenance. In the gametophytic tissue, antheridia and archegonia are somewhat submerged.
Sporophytes generate from the parent gametophyte and continue to develop throughout the plant’s life. Stomata and sporophytes are present in many of them in Hornwort. A single chloroplast can be present in each photosynthetic cell of the thallus. Meristem cells in the plant’s base continue to categorize and increase the plant’s height. Many hornworts form symbiotic relationships with cyanobacteria and help to fix nitrogen from the atmosphere.

Characteristics of Anthocerotopsida (Hornworts)

• The gametophytic body of hornworts is flat, dorsiventral, simple thalloid, and has no internal differentiation.
• Rhizoids are smooth-walled.
• Each cell of hornworts has one chloroplast with a pyrenoid.
• Sex organs are present dorsally embedded in the thallus.
• The columella is present within the capsule and originates from the endothecium.       

Bryopsida (Mosses) :

Bryopsida is a particular class of Bryophyta and has around 1400 species. They are also known as Mosses. Most mosses are present in wet environments. Apart from that, it requires water to reproduce, hence they usually developed into cushions or mats. Mosses provide food and shelter for small animals as well as larger herbivores like the musk ox. They also help in preventing soil erosion and help the soil retain moisture and minerals. Because they are sensitive to pollution, mosses are used to test the quality of the air. Examples include Sphagnum, Funaria, and Polytrichum.

Characteristics of Bryopsida (Mosses)

• The gametophyte is categorized into protonema and foliose gametophore.
• Foliose is formed from the stem as an axis and leaves without a midrib.
• Rhizoids are multicellular with oblique septa.
• Sex organs are borne apically on the stem.
• Elaters are absent.
• The sporophyte is differentiated into foot, seta and capsule.
• Sporogenous tissues develop from endothecium.
• The columella is present.
• Separation of the lid is the result of the Dehiscence of the capsule.

Characteristics of Bryophytes

• Bryophytes Plants developed in damp and shaded places.
• They are free from the true vegetative structure and are present in root-like, stem-like and leaf-like structures.
• The haploid gametophyte is the major segment of the plant body.
• Multicellular sex organs are present in the photosynthetic gametophyte. The antheridium is generated by flagellated antherozoids.
• The zygote becomes a multiple-celled sporophyte. The sporophyte is a semi-parasitic organism that depends on the gametophyte for its nutrition.
• Sporophyte cells undergo meiosis to produce haploid gametes that create a gametophyte. 
• An archegonium is structured like a flask and produces one egg. Antherozoids are connected with eggs to create a zygote.