Bryophytes order sphagnales

This presentation usefull for post graduate and gradutes students of botany.

1. Sphagnales
Bryophytes

2. Bog mosses or peat mosses
Commonly c/as ‘bog mosses or peat mosses’

Bog: Badly drained permanently wet land with high rainfall
Common in upland and waste areas of temperature regions

Peat: Partially decomposed plant material
Common in areas with poor drainage
Department of Botany JES College Jalna

3. Distribution and Habitat
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Only genus – Sphagnum, a bog moss
Some called as turf moss

Cosmopolitan – north & south tropics, through temperate
regions extending to sub-arctic and sub-antarctic regions

Dense masses in ponds, lakes which contain little amount of
lime
In cooler cliamtes – dominates the vegetation
350 Species
> 20 in India
Department of Botany JES College Jalna

4. Distribution and Habitat
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Grows in water with pH range from 3.7 to 4.9
Size – few inches to 7 inches

Perennial moss: Older parts die regularly and in combination
with the remains of other surrounding plants, form a
compact mass k/as peat

Since, Peat former – great commercial importance
Department of Botany JES College Jalna

5. Mature Gametophyte
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Erect, branched – differentiated into
stem & leaves
Rhizoids – colourless, survive for a
short time
Apex – posses no. of densely crowded
short branches called ‘coma’

Posteriorly, branches arise in tufts in
axil of every fourth leaf
Each tuft – 3 to 8 branches
Divergent branches: Short, stout,
outward & upward
Drooping or flagelliform branches:
Hang downward, close & around the
stem (absent in submerged forms)
Department of Botany JES College Jalna

6. Mature Gametophyte
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Sometimes, one branch in tuft
grows & develops into an apical
cluster of branches as the main
stem
This is called ‘innovation’
When separates from main plant –
grows into an independent plant

The first formed lvs .are 3-ranked
Arrangement turns to 2/5 in the
later stages

Exceptional feature of Sphagnum –
absence of midrib
Department of Botany JES College Jalna

7. Reproduction
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Vegetative reproduction
Innovations
Some multiply by primary protonema :- Few thalloidal
cells of primary protonema become meristematic & forms
multicellular filament

This develops into a thallus-like, flat secondary protonema

•Sexual reproduction
•Both monoeciuos and dioecious species
•Antheridia – on Antheridial or Male branches
•Archegonia – on Archegonial or Female branches
Department of Botany JES College Jalna

8. Reproduction
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Antheridial or Male Branches
Catkin-like small structures
Arranged spirally or in straight
rows on main axis
Possess many small, coloured lvs -
Yellow, brown or reddish
Axil of each leaf – antheridial
branch develops antheridium –
acropetally
Department of Botany JES College Jalna

9. Reproduction
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Mature Antheridium
Long stalk & globular body
Stalk – 2 to 4 rows of cells
Single layered sterile jacket
enclosing androcyte cells

Androcyte – metamorphoses into
biflagellate, unicellular, uninucleate
antherozoid
Antheridium – dehisces by several
irregular lobes or valves at the apex
Department of Botany JES College Jalna

10. Reproduction
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Archegonial Branches
Shorter than antheridial branches
Bud-like strcutures bearing single
or 2-5 archegonia surrounded by
lvs.
Lvs – green & larger than lvs of
vegetative branches
These are c/as ‘perichaetium’

Primary archegonium : develops
from apical cell
Secondary archegonia : develop
from derivatives of apical cell
Department of Botany JES College Jalna

11. Reproduction
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Mature Archegonium
Long stalk, twisted neck & a massive
venter
Neck jacket : 2-3 celled thick in base &
middle parts
8 or more cover cells at apical part

Neck cavity: 8-10 neck canal cells
Venter: single venter canal cell and an
egg
Department of Botany JES College Jalna

12. Reproduction
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Mature Sporophyte
Contains foot, seta & capsule

Foot : Parenchymatous; bulbous or
cylindrical body; haustorial in function
Seta: ill-developed; inconspicuous and
has very narrow structure
Capsule: Well-developed, quite
conspicuous & spherical
Dark-brown or black coloured
Has 2-7 layered wall
Outer layer – epidermis with several
nonfunctional stomata
Department of Botany JES College Jalna

13. Reproduction
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Mature Sporophyte
Capsule wall with chloroplasts
Operculum : at apical part of the capsule (It
is a circular, biconvex disc-shaped
structure)
Annulus : circular groove of thin-walled
cells separates the operculum from capsule

•Columella : central part of the
capsule; made up of sterile cells
•Dome-shaped arch of fertile
sporogenous tissue is present over
the columella
•Calyptra & perichaetium surround the
sporophyte in young conditions

Department of Botany JES College Jalna

14. Reproduction
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Mature Sporophyte
•At maturity, axis of archegonial
branch elongates and capsule comes
out of calyptra & perichaetium
•The leafless, elongated axis of the
archegonial branch, at the base of
sporophyte is c/as pseudopodium
It is mainly a post-fertilization devt
•A sac-like structures from the distal
end of the pseudopodium & basal
part of the calyptra, is k/as vaginula
•Foot remains embedded in the
vaginulla
Department of Botany JES College Jalna

15. Reproduction
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Dehiscence of capsule
•Capsule dehisces by ‘air-gun mechanism’
•Due to heat of the sunny day, columella &
the capsule wall become dry and get
shrivelled
•It develops air space under the spore sac
•Capsule changes its shape from spherical
to cylindrical
•Air inside the capsule gets compressed,
and a pressure also develops inside the
capsule
•Due to this, operculum breaks off at the
aanulus
•Spore sac ruptures and the spores are
blown to a height of several centimetres
Department of Botany JES College Jalna