Classification of Bryophytes – Imaluop

Now we are going to discuss classification of bryophytes, the amphibians of plant kingdom with characteristic features of each category with their individual examples but before we study more you know basic information about general characteristics of bryophytes.  

Classification of Bryophytes: 

Bryophyta can be divided into three classes – hepaticopsida or liverworts, anthocerotopsida or Hornwort, bryopsida or moss and we will discuss characteristics features of each class along with their mode of reproduction and examples. 

Class Hepaticopsida Also Know As Liverworts: 

Characteristics of Hepaticopsida: 

• Their name Hepaticopsida comes from the word hepatic which suggests the liver and this class of hepaticopsida is either folliose or thallus-like structure. 
• The thallus plant body of hepaticopsida show dichotomous branching and their body structure is dorsoventrally flattened lobe like and on ventral side unicellular, septate, branched root like structure rhizoids present for soil anchorage.  
• On dorsal side of thallus plant body hepaticopsida have male and female reproductive organs and the sporophytic plant body develop from zygote but their sporophytic plant body is not always have foot, seta and capsules, in case of Riccia only capsules present. 
• But in general their sporophytic plant body is divided into foot, seta and capsules as seen in Marchantia, their capsules do not have columella and the sporogenous tissue is formed by endothecium.  

Mode of Reproduction in Hepaticopsida: 

When a part of their body break from the main body then the detached part can give rise to new plant body by the means of vegetative reproduction in which the plant body produce a special structure, Gemma cup and multicellular, photosynthetic gemmules are formed inside the Gemma cup and another mode of vegetative reproduction is fragmentation. 

Male and female reproductive organs may present in single thallus or on separate thallus and male reproductive organs and female reproductive organs produce movable flagellate antherozoid and eggs respectively.

Upon fusion of movable male gametes and non movable female gametes inside the archegonium produce diploid zygote which gives rise to semi parasitic diploid sporophytic plant body and the sporophytic plant body produce spore which gives rise to independent photosynthetic gametophyte plant body. 

Examples of Hepaticopsida:  

Some important examples of class hepaticopsida are Marchantia, Riccia, Porella, Sphaerocarpos, Pellia, Calobrium among them Riccia and Marchantia belong to order Marchantiales, Pellia belong to order Jungermanniales, Sphaerocarpos belong to order Sphaerocarpales while Calobrium belong to order Calobryales. 

Class Anthocerotopsida Also Known As Hornworts: 

Characteristics features of Anthocerotopsida: 

• Anthocerotopsida are also known as Hornworts and their thallus-like plant body is dorsoventrally flattened with smooth walled rhizoids. 
• Reproductive organs present on the dorsal side of their gametophytic plant body and their chloroplast have a special structure called a pyrenoid. 
• Their sporophytic plant body has a capsule with columella and a special structure pseudoelater present in their capsules and the sporogenous tissue of class anthocerotopsida is developed from amphithecium. 

Modes of Reproduction in Anthocerotopsida: 

Under unfavorable conditions anthocerotopsida show vegetative reproduction by formation of tuber and fragmentation is also a mode of vegetative reproduction in anthocerotopsida. 

Like other members of bryophyta their antheridium produce motile flagellated male gametes which swim and reach upto the female reproductive organs archegonium and fuse with eggs to form diploid zygote which grow further to form diploid spore and the spore late give rise to gametophytic plant body which are capable of photosynthesis. 

Examples of Anthocerotopsida: 

Some prominent members of class anthocerotopsida are Anthoceros, Megaceros, Notothylas and all of those belong to the only one order of class anthocerotopsida, anthocerotales. 

Class Bryopsida Also Know As Mosses: 

Characteristics Features of Bryopsida: 

• Their gametophytic plant body is either thread like protonema or foliose body which have stem-like structure axis and leaves like structure and their multicellular rhizoids show oblique septa. 
• Reproductive organs are present on their foliose gametophytic plant body over the stem like axis and their sporophytic plant body is differentiated into three parts: foot, seta and capsules while their capsules have columella and elater are absent. 
• Their capsules have a lid which removes during dehiscence and it causes forceful dispersal of spores in their surroundings and the sporogenous tissue is developed from endothecium. 

Modes of Reproduction in Bryopsida: 

Budding is a special mode of vegetative reproduction in their lifecycle and fragmentation of secondary protonema also can give rise to new gametophytic plant bodies. 

Like anthocerotopsida and hepaticopsida, bryopsida also have male reproductive organ antheridium and female reproductive organ archegonium which produces male gametes or antherozoid and female gametes or eggs which fuse to form diploid zygote and the diploid zygote produce diploid sporophytic plant body and the sporophytic plant body produce spore and the spore again produce gametophytic plant body.  

Examples of Bryopsida: 

Some important members of class Bryopsida are Funaria, Sphagnum, Polytrichum and the class Bryophyta can be divided into five orders – Bryales, Andiales, Sphagnales, Polytrichales and Baxbaumiales.