Classification of Bryophytes - Practice Questions & MCQ

Bryophytes are divided into three classes

1. Hepaticopsida (Liverworts)
2. Anthoceropsida (Hornworts)
3. Bryopsida (Mosses)

Hepaticopsida: 

• Members of this class are also called liverworts. 
• Liverworts are mostly found in moist and shady localities. 
• The gametophyte can be either thalloid (Riccia, Marchantia) or can have leaf-like appendages in two rows on a stem-like axis (Porella).
• The thallus is dorsiventral, prostate and has unicellular rhizoids (smooth walled and pegged) and multicellular scales known as Amphigastria on the ventral side. 
• Dichotomous branching is seen in Riccia and Marchantia.
• Vegetative reproduction is by fragmentation or by the formation of multicellular green structures called Gemmae (Marchantia).
•  During sexual reproduction, antheridia and archegonia are formed on the same thallus (Riccia) or on different thalli (Marchantia).
• The sporophyte is usually complete parasite on gametophyte and has no columella. It has foot and capsule or foot, seta and capsule. 
• Sterile, unicellular sporogenous cells with spiral wall thickenings known as Elaters are formed in the capsule of some liverworts like Marchantia. These help in Spore dispersal.

Anthoceropsida:

• Members of Anthoceropsida are commonly called as Hornworts because their sporophyte emerges out of the gametophyte in the form of an elongated horn-like structure.
• The gametophyte is dorsiventral with unicellular rhizoids but without scales. 
• Thallus of these bryophytes is generally associated with blue-green algae such as Nostoc.
• Vegetative reproduction occurs through fragmentation.
• Antheridia and Archegonia are formed singly or in groups on the dorsal side in special chambers.
• Sporophyte has foot, intercalary meristematic zone and capsule. 
• Sporophyte is partially parasitic on gametophyte
• Capsule possess columella and Pseudoelaters.
• Pseudo elaters help in spore dispersal.
• Ex: Anthoceros, Notothylas
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Bryopsida:

• These are also known as mosses.
• The gametophyte has two stages in the life cycle one is protonema and other is gametophore. 
• Protonema is prostate, branched filamentous structure which looks like alga. It is formed from spore.
• Gametophore is adult erect leafy gametophyte that develops from adventitious buds of protonema.
• Rhizoids are multicellular and branched. Scales are absent.
• Gametophore has Stem-like structure called cauloid and leaf-like structures called phyllodes. Phyllodes are arranged in an alternate manner on the stem.
• Vegetative reproduction takes place by fragmentation, gemmae formation and by secondary protonema formed from wounded parts of gametophore.
• Sex organs arise in groups at the apex of the stem and its branches and are interspersed by multicellular, uniseriate green structures called paraphyses.
• The sporophyte is partially parasitic on gametophore and differentiated into foot, seta and capsule.
• Capsule possess peristomial teeth which help in spore dispersal by showing hygroscopic movements. The capsule also possesses columella interior to spore sac.
• Ex: Funaria (Cord moss or Fire moss), Sphagnum (Peat or Bog-moss).
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