Bryophyta

Jun 22, 2023, 16:45 IST

A living biological system that performs as a distinct entity is called an organism. An organism is deemed to be alive when it engages in one or more of the numerous life processes. Living organisms can be distinguished from non-living objects by the presence of life processes. Life processes carried on by living things include sensitivity, excretion, growth, breathing, mobility, growth, and reproduction. Cells comprise all living things. Organisms are categorized by taxonomy into groups like protists, bacteria, and other unicellular microbes, as well as multicellular animals, plants, and fungi. In this article, we will discuss the plant species Bryophyta in detail.

Introduction

• As members of the plant kingdom that may survive in soil but require water for sexual reproduction, bryophytes are also referred to as amphibians of the plant kingdom.
• Land plants, especially non-vascular ones, are referred to as embryophytes in the grouping of green plants known as Bryophyta.
• These are tiny plants that thrive in moist, shaded environments. They don't have any vascular tissues. They do not reproduce by blooms or seeds, but rather through spores.
• The plant body is thallus-like, prostrate, or upright, and is attached to the substrate by unicellular or multicellular rhizoids.
• The single characteristic that may be used to identify a bryophyte is the lack of real vascular tissue. Some have specialized tissues that move water, but because they lack lignin, they are not regarded as real vascular tissues.
• The first genuine plants are believed to have evolved from bryophytes, which are thought to have descended from charophytes.
• The term "gametophyte" refers to the haploid, gametophytic primary plant body of a bryophyte.
• The female sex organ is flask-shaped and produces a single egg, whereas the male sex organ, known as the antheridium, generates biflagellate antherozoids.
• For instance, bryophytes are a group that includes about 20,000 species of plants. The three types of bryophytes are mosses, hornworts, and liverworts.
• Examples of common liverworts are Marchantia, Riccia, Pellia, Porella, Sphaerocarpos,
• Calobryum, Funaria, Polytrichum, and Sphagnum are examples of mosses
• Hornworts include Anthoceros, Notothylas, and Megaceros.

Characteristics

• The thallus-like plant body can be either prostrate or erect. They have root-like, stem-like, and leaf-like structures but no genuine vegetative structure.
• Rhizoids, which can be single or multiple-celled structures, attach to it.
• There is no vascular system in plants (xylem, phloem). And in moist, shaded conditions, plants flourish.
• The haploid gametophyte predominates in the structure of the plant.
• Rhizoids, axis, and leaves make up the three components of the thalloid gametophyte.
• The multicellular sex organs are present in photosynthetic gametophytes. Flagellated antherozoids are produced by antheridium.
• The zygote develops into a multiple-celled sporophyte. The sporophyte is a semi-parasitic creature that is dependent on the gametophyte.
• A gametophyte is created when sporophyte cells undergo meiosis to create haploid gametes.
• The term used to describe the young gametophyte is protonema.

Classification

The three classes of Bryophytes that are based on the most recent classification include:

• Anthocerotopsida (Hornworts)
• Hepaticopsida (Liverworts)
• Bryopsida (Mosses)

Anthocerotopsida (Hornworts)

There are about 200-250 species in this class. They are also known as hornworts. Anthocerotales is the only order it has. Anthoceros, Megaceros, and Notothylas are a few examples.

The following are the main characteristics:

• The gametophytic body is an undifferentiated, plain, flat, dorsiventral thalloid.
• Sexual organs are dorsally implanted in the thallus. One pyrenoid-containing chloroplast can be found in every cell.
• The foot, the meristematic zone, and the capsule make up the three sections of the sporophyte.
• Sporogenous tissues develop from amphithecium. Cells in rhizoids have smooth walls.
• The capsule, which is formed of endothecium, contains the columella. Pseudocraters can be found in the capsule.

Hepaticopsida (Liverworts)

This class of bryophytes contains liverworts. It includes about 900 different species. The most primitive bryophytes are liverworts. They prefer to live in moist soil and rocks. They have a much lower likelihood of drying out because they reside close to water.

Hepaticopsida is divided into four additional orders:

• Marchantiales (e.g. Riccia, Marchantia)
• Sphaerocarpales (e.g. Sphaerocarpos)
• Calobryales (e.g. Calobryum)
• Jungermanniales (e.g. Pellia)

Bryopsida (Mosses)

With almost 1400 species, Bryopsida (Mosses) is the biggest class of Bryophyta. They are frequently called mosses. Funaria and Sphagnum are common examples.

The following are the main characteristics:

• The gametophyte is a protonema or foliose gametophore. Foliose plants have leaves without a midrib and a stem that serves as an axis.
• Multicellular rhizoid formations feature oblique septa.
• The sex organs are carried apically on the stem in the absence of elaters.
• The three types of sporophytes are foot, seta, and capsule.
• Sporogenous tissues develop from the endothecium.
• The detachment of the lid causes the capsule to dehisce, and Columella is visible.

Reproduction

Sexual reproduction

The male and female reproductive organs, antheridium and archegonium, may coexist on the same or distinct thalli. Both of them generate eggs and sperm. A zygote develops following fertilization. A few sporophyte cells go through meiosis to produce haploid spores after the zygote develops into a diploid sporophyte. Haploid gametophytes, which are free-living, photosynthetic creatures, are created from these spores.

Asexual reproduction

This process happens through the fragmentation process or gemma production. Gemma cups are where gemmae are made. Gemmae are asexual, multicellular, and green in color. The gemma cup separates from the parent plant and develops into a new plant.

The following are the primary traits of the Hepaticopsida class:

• A thalloid or foliose plant can be a gametophyte.
• Lobed, dichotomously branching, and dorsiventral thalloid forms
• Dorsally positioned inside gametophytic tissues are the sex organs.
• Only the capsule (in Riccia) or the foot, seta, and capsule make comprise the sporophyte (in Marchantia).
• Rhizoids are unicellular, septate, and branching.
• A columella is absent from the capsule, and the endothecium gives birth to sporogenous tissues.

Frequently Asked Questions(FAQs) Bryophyta

Q1. Does Bryophyta belong to the plant kingdom?

Ans. Yes, Bryophytes are placed under the kingdom Plantae although they are primitive and do not show true vegetative structures. The vascular bundles are absent and reproduction is mainly asexual.

Q2. What Do bryophytes produce seeds?

Ans. No, the plants placed under Bryophta are primitive and seedless that do not produce any seeds, flowers, or fruits. Sexual reproduction is carried out through the help of spores which do not result in seed formation.

Q3. Which groups are included in Bryophyta?

Ans. Brophyta contains three main categories of planta called Liverworts, Mosses, and Hornworts and all these groups lack vascular structures and are seedless.

Q4. When was Bryophyta discovered?

Ans. Bryophytes were first identified in the year 1851 by Wilhelm Hofmeister who studied the life cycle of mosses and identified these spore-bearing unique plants. The term Bryophyta was coined in the year 1864.