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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