Bryophytes: Characteristics, Classes

Bryophytes are called amphibians in the plant kingdom because of their status as terrestrial; however, they require water for their life cycles at the time of sexual reproduction. Thus, they carry out their wheel of life in both water as well as on land. The term Bryophyta originates from the word ‘Bryon,’ meaning mosses, as well as ‘phyton’ meaning plants.

Bryophyta consists of embryophytes like mosses, hornworts, as well as liverworts. These are tiny plants that grow in shady as well as moist areas. They are devoid of vascular tissue. The flowers or seeds are not found, instead, they reproduce by spores. Research into bryophytes is known as bryology.

General Characteristics of Bryophytes:

• The plant body is thallus-like, i.e., prostrate or erect.

• They do not have a true vegetative structure as well as have a root-like, stem-like and also leaf-like structure.

• Plants lack the vascular system that consists of the xylem as well as phloem.

• It is connected to the substratum with rhizoids. They are multicellular or unicellular.

• Bryophytes reveal alternation of generation between independent gametophytes with sex body organs, which produce sperm and eggs, and reliant sporophyte, which consists of spores.

• Sporophytes are semi-parasitic and depend on gametophytes to provide their nutrition.

• The sporophyte is separated from the feet, seta and capsule.

• Cells of sporophytes undergo meiosis to create haploid gametes, which create a gametophyte.

• The gametophyte is a haploid, which is the dominant component of the plant body. The juvenile gametophyte is referred to as protonema.

• The thalloid gametophyte is differentiated right into rhizoids, axis, as well as leaves. Gametophytes have multicellular sexual body organs and are photosynthetic.

• Antherozoids are formed by the antheridium, which is biflagellate.

• The shape of an archegonium resembles a flask and generates one egg.

• The antherozoids fuse with the egg to form a zygote.

• The zygote develops into a multicellular sporophyte. Plants take place in damp as well as shaded areas.

Bryophyta is separated right into the adhering to three classes according to the most recent category:

Hepaticopsida: Liverworts come under this class.

1. 1. 1. 1. The thalloid or foliose gametophyte plant.
         2. Foliose leaf types have no midrib and are dorsiventral.
         3. Lobed, and dichotomously branching, the thalloid.
         4. Each thallus cell has a large number of chloroplasts but no pyrenoids.
         5. Rhizoids are single-celled, branching and aseptate.
         6. The sex organs are carried dorsally in gametophytic tissues.
         7. Only the capsule or foot, seta, and capsule make up the sporophyte.
         8. The capsule is devoid of columella. The endothecium produces sporogenous tissues.
         9. Reproduction:
            1. Asexual reproduction: Asexual reproduction occurs either by fragmentation or by the formation of gemmae. Gemmae are generated inside gemma cups. Gemmae are nonsexual buds, which are green and also multicellular. The gemma cup develops into a brand-new plant after removing it from the moms and dad plant.
            2. Sexual reproduction: Antheridium is a male organ, and archegonium is a female body organ, which may be present on the exact same thalli or various thalli. They generate sperm and egg, specifically. After fertilization, the zygote is created. The zygote turns into a diploid sporophyte; a couple of cells of the sporophyte undertake meiosis to form haploid spores. These spores develop into haploid gametophytes. They are free-living and photosynthetic. 

• Further classification: Hepaticopsida is further split right into four orders:

• Marchantiales include Riccia and Marchantia. 

• Sphaerocarpales that includes Sphaerocarpos.

• Calobryales includes Calobryum.

• Jungermanniales includes Pellia.

• Bryopsida: It is the biggest class of Bryophyta with around 1400 species. They are commonly called mosses.

• The primary qualities of the class Bryopsida are:

• The gametophyte is separated into protonema and foliose gametophore.

• Foliose consists of a stem as an axis. They also have left without a midrib.

• Rhizoids are multicellular with oblique septa.

• Sex body organs are borne apically on the stem.

• Elaters are missing.

• The sporophyte is set apart right into the foot, seta, and also capsule.

• Sporogenous cells develop from endothecium.

• Columella exists.

• The separation of the cover causes dehiscence of the capsule

• Reproduction:

• Asexual reproduction: Asexual reproduction is by budding and also fragmentation of additional protonema.

• Sexual reproduction: The apical component of leafy portions contains antheridia and archegonia. After fertilisation, the sporophyte is generated, which is significantly more developed than liverworts. The spores are used to establish the gametophyte.

• Further classification: Bryopsida is additionally divided into five orders: 

• Bryales

• Andreales.

• Sphagnales.

• Polytrichales.

• Buxbaumiales.

• Anthocerotopsida: There are around 300 varieties present in this course. They are frequently called hornworts.

• The primary characteristics of the course Anthocerotopsida are:

• The gametophytic body is flat, dorsiventral, basic thalloid without inner distinction.

• Rhizoids have smooth walls in them. Each cell of it has a single chloroplast with a pyrenoid.

• Sex body organs exist dorsally installed in the thallus.

• The sporophyte is distinguished into the foot, meristematic area, and capsule.

• Sporogenous tissues establish from amphithecium. In the capsule, there is a Pseudoelaters present.

• The columella is present in the capsule, which stems from endothecium.

• Further Classification: It has only one order, i.e., Anthocerotales.

Example of Bryophyta: The following are some bryophytes examples: Marchantia, Mosses, and liverworts