Introduction
Bryophyta is derived from the Greek words ‘Bryon’ which means moss and ‘Phuton’ which means plants. Embryophytes such as mosses, hornworts, and liverworts belong to the Bryophyta family. These are tiny plants that thrive in shaded and moist environments. They are devoid of vascular tissues. Instead of flowers and seeds, they reproduce through spores. Despite the fact that most bryophytes lack intricate tissue organisation, they come in a variety of shapes and sizes, and they have a diverse ecosystem. They can be found all over the world and are modest compared to most seed-bearing plants. Bryology is the scientific study of bryophytes.
General Characteristics of Bryophytes
- Plants thrive in moist, shady environments
- The plant’s body is thallus-like, meaning it can be prostrate or upright
- Rhizoids, which can be unicellular or multicellular, attach it to the substratum
- They lack real vegetative structure and have a root-like, stem-like, and leaf-like structure
- Plants don’t have a vascular system (xylem, phloem)
- The sporophyte is divided into two parts: the foot seat and the capsule
Classification of Bryophytes
According to the newest classification, Bryophyta is split into three classes:
- Hepaticopsida (Liverworts)
- Anthocerotopsida (Hornworts)
- Bryopsida (Mosses)
1. Hepaticopsida (Liverworts):
Hepaticopsida gets its name from the word “hepatic,” which means “liver.” This category includes liverworts. This group includes liverworts, which are a form of bryophyte. It is home to over 900 species. Liverworts are the most basic bryophytes. They prefer to live in moist rocks and wet soil. They have a significantly lower likelihood of drying because they live near water.
A plant called a gametophyte is a form of gametophyte. It is often dichotomously branched and can be thalloid (flat) or ribbon-like (ribbon-like). Rhizoids, for example, connect Marchantia to the soil. Other species, such as Porella, grow upright and are deceptively leafy, meaning they have a phoney stem and leaves. The sporophyte is nourished and protected by the gametophyte. On the upper surface of the thallus, the sex organs form at the terminals of the branches. They sometimes develop different branches on gametophytes termed antheridiophores and archegoniophores, just like Marchantia.
Hepaticopsida is Further Divided into 4 Orders:
- Marchantiales (e.g. Riccia, Marchantia)
- Sphaerocarpales (e.g. Sphaerocarpos)
- Calobryales (e.g. Calobryum)
- Jungermanniales (e.g. Pellia)
The Main Characteristics of the Class Hepaticopsida are:
- The gametophyte plant can be foliose or thalloid
- Dorsiventral, lobed, and dichotomously branching thalloid forms
- Rhizoids are single-celled, branching, and septate organisms
- The sex organs are anchored dorsally in gametophytic tissues
- Only capsule (in Riccia) or foot, seta, and capsule make up the sporophyte (in Marchantia)
Reproduction
Asexual Reproduction
It occurs as a result of the development of gemmae or the fragmentation process. Inside gemma cups, gemmae are formed. Gemmae are multicellular and asexual organisms that are green in colour. After separating from the parent plant, the gemma cup grows into a new plant.
Sexual Reproduction
On the same or distinct thalli, antheridium (male organ) and archegonium (female organ) may be present. They are responsible for the production of sperm and eggs, respectively. The zygote is generated after fertilisation. The zygote matures into a diploid sporophyte, from which a few cells undergo meiosis to produce haploid spores. These spores develop into free-living, photosynthetic haploid gametophytes.
2. Anthocerotopsida (Hornworts):
During this class, approximately 300 species are present. Hornworts are the common name for them. Anthocerotales is the sole order it belongs to. Anthoceros, Megaceros, and Notothylas are among examples. In various areas, this bryophyte clade is slightly more advanced than Bryopsida and Hepaticopsida. The gametophyte is lobed and irregular from a broad perspective. Except in the early stages of growth, the sporophyte is not dependant on the gametophyte for sustenance or protection. Antheridia and archegonia are partially immersed in the gametophytic tissue.
The Main Features are:
- The gametophytic body is a basic thalloid that is flat, dorsiventral, and lacks internal differentiation
- Rhizoids have a smooth surface
- Each cell has one pyrenoid-containing chloroplast
- Sex organs are embedded in the thallus dorsally
Reproduction
Asexual Reproduction
The process of thallus fragmentation and tuber formation under unfavourable conditions are used for vegetative propagation.
Sexual Reproduction
They reproduce sexually by using watery sperm that moves from antheridium to archegonium to procreate. A sporophyte develops from a fertilised egg. The Sporophyte divides longitudinally, releasing spores that develop into gametophytes.
3. Bryopsida (Mosses):
This is a large Bryophyta class with around 1400 species. Mosses is a common name for them. Most mosses, like liverworts, like moist conditions. Unlike other bryophytes, they thrive in moderately dry settings. Mosses, on the other hand, require water to reproduce, which is why they frequently form cushions or mats. Funaria, Polytrichum, and Sphagnum are some examples.
Bryopsida is Further Divided Into 5 Classes:
- BryalesAndriales
- Sphagnales
- Polytrichales
- Buxbaumiales
The Main Features are:
- The protonema and foliose gametophore are two types of gametophytes
- Foliose is characterised by a stem that acts as an axis and leaves that lack a midrib
- Rhizoids have oblique septa and are multicellular
- The sex organs are located on the stem apically
Reproduction
Asexual Reproduction
Budding and fragmentation of the secondary protonema are used for asexual reproduction.
Sexual Reproduction
Antheridia and archegonia are found at the apical section of leafy stems for sexual reproduction. Sporophyte, which is more distinct than liverworts, is generated after fertilisation. The spores give rise to the gametophyte.
Importance of Bryophytes
- The first organisms to inhabit rocks were mosses and lichens
- They break down the rock, making it ideal for higher plant development. The acidic secretion that causes the death and decomposition of mosses is responsible for soil formation
- Bryophytes are densely growing plants that act as soil binders
- In bog succession, mosses play a critical role. Due to the presence of water and humus, the dense moss mat provides an ideal substratum for the germination of hydrophilic seeds. Meanwhile, the mosses and hydrophilic plants that have died and rotted produce a solid soil for mesophytic development
- They reduce the impact of falling rain on the land, preventing erosion
- Because of their water-holding capacity, they limit the amount of run-off water
- They aid in the nutrient recycling process
- They play the role of a rock builder. These plants break down bicarbonate ions, causing insoluble calcium carbonate to precipitate. The mineral deposit is still growing, and it now covers several hundred square feet
- Sphagnum is used to fill absorptive bandages in place of cotton for the treatment of boils and wound discharge because it has a strong absorptive power and a few antimicrobial characteristics
- Marchantia has been used to treat pulmonary tuberculosis and liver disease
- In the treatment of acute bleeding and eye infections, a decoction of dried sphagnum is employed
- Peat-tar is used as a preservative and antiseptic. Polytrichum species have been found to dissolve kidney and gallbladder stones
- Antibiotic compounds are frequently isolated from antibiotic-producing bryophytes
- Dry mosses are ideal for storing fragile items like glassware and bulbs. Water retention capacity is required for the transshipment of living material such as cuttings and seedlings
- Herbivorous animals, birds, and other mammals eat mosses as a source of food
- Sphagnum is also known as sphagnum, which is a type of peat. Peat is created by delaying the breakdown of organic matter. Peat is a dark-colored substance formed by the slow compaction and carbonization of partially degraded plant debris in bogs
- Lower layers of peat from coal are used as fuel, and peat is also used to make ethyl alcohol, ammonium sulphate, ammonia, colour, paraffin, tannins, and other products. In horticulture, it increases soil texture
Conclusion
Embryophytes such as mosses, hornworts, and liverworts belong to the Bryophyta family. These are tiny plants that thrive in gloomy, moist environments. They are devoid of vascular tissues. They don’t generate flowers or seeds, instead relying on spores to proliferate. Bryology is the scientific study of bryophytes. Because they are terrestrial plants that require water to complete their life cycle at the time of sexual reproduction, bryophytes are known as “plant amphibians.”