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General Characters & Classification of

BryophytesBryophytes

General Characters

�The word bryophyte is the collective termfor mosses, hornworts and liverworts

�Bryology is the study of bryophytes.

�Includes the simplest and most primitiveland plants.

�Plants lack true vascular system, hencecalled non-vascular plants.

�Terrestrial but need water to complete life-cycle, hence called amphibians of plantkingdom.

�Mostly, grow on shady damp places.

General CharactersGametophytic Plant Body

�Dominant plant body is gametophytic (n).

�Thalloid plant body i.e. not differentiatedinto true roots, stem and leaves. Or leafyshoots are present.

�Plants are green and possesschloroplasts.

�Roots are absent, replaced by unicellularor multicellular rhizoids.

�Vascular tissue completely absent.

Structure: GametophyteGametophore – leafy structure or thick, conspicuous part

Moss gametophore

Leafy Liverwort

Thallose liverwort

General CharactersReproduction

�Always oogamous

�Male gamete is small and motile, femalegamete is large and non-motile.

�Male reproductive organs are antheridiaand female are archegonia.and female are archegonia.

�Both are multicellular and jacketed.

�Antheridia are differentiated into stalk, andbody.

�Archegonia are stalked and differentiatedinto venter and neck.

Antheridium

Archegonium

Antheridium

General CharactersSporophyte

�Represents diploid zygote, the first cell ofsporophytic generation.

�Totally dependant on gametophyte.

�In most, differentiated into foot, seta andcapsulecapsule

�The sporophyte produce haploid spores.

�The spores fall on suitable substratum &germinate to produce gametophytic plantbody.

Sporophyte

Moss

Liverwort Hornwort

General Characters

Young gametophyte

�The haploid spores represent first cells�The haploid spores represent first cellsof gametophyte.

�Spore fall on suitable medium andgerminate to produce gametophyticplant body.

General Characters

Life cycle : 2 phases

�The haploid gametophytic generation(The gametophyte).

�The diploid sporophytic generation (Thesporophyte).

General CharactersAlternation of generation

* Division HEPATICOPSIDA - the Liverworts

Classification of Bryophytes

* Division ANTHOCEROTOPSIDA - the

Hornworts

* Division BRYOPSIDA - the Mosses

Three groupsMosses Hornworts

Leafy liverwort

1. Hepaticopsida – the liverworts

The Four Classes of Hepaticopsida

* Calobryales

Classification of Bryophytes

* Calobryales* Jungermanniales

*Marchantiales

* Metzgeriales

Classification of Bryophytes

1. Hepaticopsida – the liverworts

• So-called because the thallus of many liverworts resembles the lobes of a liver; ending “wort” means “herb”.

•Liverworts lack conducting elements (cuticle & stomata)•Liverworts lack conducting elements (cuticle & stomata)

•The gametophyte can be “thallose” or “leafy” (Jungermanniales)

• The thallus usually has some internal differentiation in the form of photosynthetic cells, air chambers and storage tissues

•The sporophyte is compact, without or a short seta

•The capsule (sporangium) has a single-layered wall

Classification of Bryophytes

2. Anthocerotopsida – the hornworts

•So-called because many hornworts have elongated horn-like structure, which is the sporophyte.

•The gametophyte may be as rosette or ribbon-like thallus

•Many hornworts develop internal mucilage-filled cavities•Many hornworts develop internal mucilage-filled cavitiesinvaded by photosynthetic cyanobacteria, especiallyspecies of Nostoc.

•Such colonies of bacteria growing inside the thallus givethe hornwort a distinctive blue-green color.

•The horn-shaped sporophyte grows from an archegoniumembedded deep in the gametophyte.

• In mature sporophyte, a multicellular outerlayer, a central rod-like columella running upthe center, and a layer of tissue in betweenthat produces spores and pseudo-elaters are

Classification of Bryophytes

2. Anthocerotopsida – the hornworts

the center, and a layer of tissue in betweenthat produces spores and pseudo-elaters arepresent.

• The pseudo-elaters are multi-cellular, unlikethe elaters of liverworts. They have helicalthickenings that change shape in response todrying out; they twist and thereby help todisperse the spores.

• It is the largest class of mosses, containing95% of all moss species.

• The gametophyte is differentiated into

Classification of Bryophytes

3. Bryopsida– the mosses

• The gametophyte is differentiated intoprostrate protonema and erect radial leafyshoot, persistant leaves spirally arrangedon stem, rhizoid with muticellualr obliquesepta.

• Sporogonium is differentiated into foot,seta and capsule.

• The most important characteristic of theBryopsida is the architecture of the ring ofteeth (peristome) surrounding the mouth ofthe sporophyte capsule.

Classification of Bryophytes

3. Bryopsida– the mosses

the sporophyte capsule.

• Bryopsida are the only mosses that have anarthrodontous peristome, i.e., a peristomein which the teeth are structured byarticulated cell wall remnants.

2. Bryopsida – the mosses

* Sphanidae* Andreaeidae

* Bryidae

Classification of Bryophytes

* Bryidae