Structure and life cycle of
Batrachospermum
Ms. Inderveena Sharma
H.O.D.
Botany Department
P.G.G.C.G. 11, Chd.
Batrachospermum
• A freshwater red algae ranging
in color from violet to bluegreen
• 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
glomerules
An 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
trichogyne
through
spermatium.
migrates into
opening
in
• 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
Batrachospermum
A-D: Germination of carpospore
E-F: Monosporangia and monospore
Life cycle
Batrachospermum
Thank you!