Structure and life cycle of Batrachospermum - P.G.G.C.G ...cms.gcg11.ac.in/attachments/article/115/Batrachospermum.pdf · •A freshwater red algae ranging in color from violet to

Structure and life cycle of

Batrachospermum

Ms. Inderveena SharmaH.O.D.

Botany Department

P.G.G.C.G. 11, Chd.

Batrachospermum

• A freshwater red algae ranging

in color from violet to blue-

green

• Though Batrachospermum is

classified with the

Rhodophyta, it really does not

look Red at all!

• Multicellular, filamentous, branched and heterotrichous

(differentialted into prostrate and erect systems)

• Thalli look like beaded filament which bear dense whorls of

branchlets, resembling beads on a string.

• They occur in the form of thick mucilagenous masses and

appear as spawn, hence commonly called frog-spawn.

• Main axis is monopodial or show pseudo-dichotomy

• Filament shows nodes and internodes

• Lateral branches arise from nodes

Branching in

Batrachospermum

• 2 main kinds of lateral

branches

• Branches of unlimited

growth

• Branches of limited

growth

Whorls of lateral

branches of limited

growth are called

glomerulesAn apical portion of thallus of

Batrachospermum showing 2 types

of branches

Enlarged

portion of

node

showing

origin of

branches

Asexual Reproduction• Occurs by non-motile monospores in monosporangia

produced only in juvenile stage of gametophytic thalli

• The terminal cell of short lateral branches of Chantransia

stage develop monosporangia, terminal cell swells and its

contents metamorphose into uninucleate monospore

• Monospore liberated from monosporangium germinates

into the Chantransia stage.

Chantransia stage (young protonemal stage of

Batrachospermum)

At this stage, gametophytic thallus resembles another algae –

Chantransia and therefore this stage is called Chantransia

stage

• At this stage, gametophytic thallus is small,

microscopic, filamentous and heterotrichous

Sexual reproduction (oogamous)

Male sex organs: spermatangia (antheridia)

Female sex organs: carpogonia

Carpogonia

Borne terminally on short carpogonial branches

Any basal cell of primary branch of limited growth starts

behaving as initial of carpogonial branch (procarp) which

divides to form carpogonial branches. The terminal cell of

this branch becomes modofied into flask shaped

carpogonium.

The upper neck shaped part is called trichogyne

The nucleus lies in swollen basal portion which divides into

two. One remains in the carpogonium and functions as egg

nucleus, other nucleus degenerates

A-B: Development of carpogonial branches

C: single carpogonial branch with young carpogonium

Spermatangia• Borne in clusters on short spermatangial branches

• Spermatangial branches arise in same way as

branches of limited growth

• Terminal cell of each branch behave as

spermatangium mother cell which bears mother cell

• spermatangium mother cell produce 1-2

spermatangia

B: Development of antheridium

C: Single mature antheridial

branch showing spertangium

Fertilization

• The male nucleus migrates into

trichogyne through opening in

spermatium.

• The male nucleus divides into two in

trichogyne, one moves downwards and

fuses with egg nucleus to form zygote.

A: Female branch showing terminal carposporangia

B: Liberation of carposporangia

C: Portion of thallus showing cystocarps

Fertilization

and post

fertilization

changes in

Batrachosp-

ermum

A-D: Germination of carpospore

E-F: Monosporangia and monospore

G: Chantransia stage

Life cycle

Batracho-

spermum

Thank you!