dr. uttam kumar kanp c1t vaucheria

BOTANY: SEM – I, PAPER

Vaucheria: Occurrence, Range of thallus organization, cell structure,

Reproduction and Life Cycle

Dr. Uttam Kumar Kanp

Systematic Position:

Class: Chlorophyceae

Order: Siphonales

Family: Vaucheriaceae

Genus : Vaucheria

Occurrence of Vaucheria:

Vaucheria is represented

Vaucheria is found mostly in fres

found on moist soil.

The terrestrial species like

places in green houses. V. amph

winter ice in U.S.A. The common

polysperma, V. sessilis and V. unci

Thallus Organization:

The thallus is made of long, cylindrical well branched filaments. The

coenocytic structure. The thallus is attached to

branched holdfast called the haptera. The thallus of V. mayyanadensis is differentiated in

subterranean branched rhizoidal system and an erect aerial system. The filaments are

interwoven and appear as dark green felt like structure.

Some species like V. debar

lateral or dichotomous. The filame

along the entire length of thallus t

(Fig. 1A, B). The septa formation

I, PAPER-C1T: PHYCOLOGY AND MICROBIOLOGY, UNIT

VAUCHERIA


Reproduction and Life Cycle

Dr. Uttam Kumar Kanp

by 54 species of which about 19 species a

esh water but about six species are marine and

V. sessilis and V. terrestris form green mats on

phibia is amphibous. V. jonesii was reported by

ommon Indian species of Vaucheria are V. amphibi

cinata etc.

The thallus is made of long, cylindrical well branched filaments. The filament is aseptate,

coenocytic structure. The thallus is attached to substratum by means of branched rhizoids or

haptera. The thallus of V. mayyanadensis is differentiated in

branched rhizoidal system and an erect aerial system. The filaments are

interwoven and appear as dark green felt like structure.

ryana show calcium carbonate incrustations. Th

ents are non-septate, the protoplasm with many n

thus the coenocytic Vaucheria thallus makes siph

on occurs only during reproduction or in Gongros

PHYCOLOGY AND MICROBIOLOGY, UNIT-5:


are found in India.

some are terrestrial

moist soil in shady

y Prescott (1938) in

ia, V. geminata, V.

filament is aseptate,

substratum by means of branched rhizoids or

haptera. The thallus of V. mayyanadensis is differentiated in

branched rhizoidal system and an erect aerial system. The filaments are rough,

e branching may be

nuclei is continuous

phonaceous structure

sira condition or for

BOTANY: SEM – I, PAPER

sealing of an injury.

The thallus structure is differentiated into cell wall and protoplasm. The

thallus is thin, weak and non-elastic. The

the inner layer is cellulosic. Inner to the

central vacuole filled with cell sap runs from one end of the filament to another forming

continuous canal or siphon.

In peripheral part of protop

chloroplasts which lack pyrenoids

chromatophores.

The chromatophores in Vaucheria contain pigments, chlorophyll a,

carotenoids and an unknown xanthophyll. The pigments in

Xanthophyceae as chlorophyll b the

Many small nuclei lie in the cytoplasm inner to the layer of chloroplasts.

nuclei with respect to chloroplasts is reversed at the

contains other membrane bound cell organelle such as mitochondria, small vesicles an

stored in form of oil. The growth of filament is apical, the filament increases in

growth of all the branches.

Nature of Thallus:

The thallus of Vaucheria is branched, non

single large cell but Vaucheria cannot be


VAUCHERIA

The thallus structure is differentiated into cell wall and protoplasm. The

elastic. The cell wall is made of two layers, the outer layer is pectic and

the inner layer is cellulosic. Inner to the cell wall there is thick layer of protoplasm. A very large

filled with cell sap runs from one end of the filament to another forming

oplasm are present a large number of small o

s (Fig. 1 B). Christensen (1952) reported presen

in Vaucheria contain pigments, chlorophyll a,

carotenoids and an unknown xanthophyll. The pigments in Vaucheria are like those of

Xanthophyceae as chlorophyll b the characteristic pigment of Chlorophyceae is absent.

the cytoplasm inner to the layer of chloroplasts. The arrangement of

nuclei with respect to chloroplasts is reversed at the time of zoospore formation. The cytoplasm also

bound cell organelle such as mitochondria, small vesicles an

in form of oil. The growth of filament is apical, the filament increases in

The thallus of Vaucheria is branched, non-septate and multinucleate structure which appears like

single large cell but Vaucheria cannot be


The thallus structure is differentiated into cell wall and protoplasm. The cell wall of

layers, the outer layer is pectic and

cell wall there is thick layer of protoplasm. A very large

filled with cell sap runs from one end of the filament to another forming a

oval or disc shaped

nce of pyrenoids in

in Vaucheria contain pigments, chlorophyll a, chlorophyll e,

Vaucheria are like those of

characteristic pigment of Chlorophyceae is absent.

The arrangement of

time of zoospore formation. The cytoplasm also

bound cell organelle such as mitochondria, small vesicles and food is

in form of oil. The growth of filament is apical, the filament increases in length by apical

structure which appears like

BOTANY: SEM – I, PAPER-

considered as single cell. As in multicellular forms

number of nuclei. The apical growth takes place. Hence

Vaucheria should be considered as

Reproduction in Vaucheria:

Reproduction in Vaucheria takes plac

(i) Vegetative Reproduction in Vaucheria:

The vegetative reproduction takes place by fragmentation. The thallus can

fragments due to mechanical injury or insect bites etc. A

to seal the injury. The broken fragment develops thick wall and later on develops into Vaucheria

thallus.

(ii) Asexual Reproduction in Vaucheria:

The asexual reproduction takes place by formation of zoospores,

(a) By Zoospores:

The zoospores formation is the most common method of reproduction in

terrestrial species it takes place when the plants are

favourable seasons or can be induced if aquatic species a

from running water to still water.

Zoospores are formed sing

development of zoosporangium b

large number of nuclei and chlorop

protoplasmic region becomes visi

cytoplasm of thallus.

Each separated protoplast secretes

cross wall. Inside zoosporangium the vacuole decreases, the

dense and round off. The change takes

nuclei become peripheral and chloroplasts enter in inner layer of cytoplasm.

The entire protoplasm of

each nucleus two flagella are pro


VAUCHERIA

considered as single cell. As in multicellular forms mitotic divisions take place increasing the

number of nuclei. The apical growth takes place. Hence the aseptate coenocytic structure of

Vaucheria should be considered as acellular coenocyte.

Reproduction in Vaucheria:

Reproduction in Vaucheria takes place by vegetative, asexual and sexual methods.

Vegetative Reproduction in Vaucheria:

The vegetative reproduction takes place by fragmentation. The thallus can

fragments due to mechanical injury or insect bites etc. A septum develops at the

fragment develops thick wall and later on develops into Vaucheria

Vaucheria:

The asexual reproduction takes place by formation of zoospores, aplanospores and akinetes

The zoospores formation is the most common method of reproduction in

terrestrial species it takes place when the plants are flooded. Zoospore formation takes place in

induced if aquatic species are transferred from light to darkness or

gly within elongated club shaped zoosporangium

begins with a club shaped swelling at the tip o

oroplasts along with the cytoplasm move into

ible at the base of cytoplasm and it is separate

Each separated protoplast secretes thin membrane and zoosporangium gets

cross wall. Inside zoosporangium the vacuole decreases, the contents of sporangium become very

dense and round off. The change takes place in relative position of chloroplasts and nuclei, the

peripheral and chloroplasts enter in inner layer of cytoplasm.

the zoosporangium contracts to form oval zoo

roduced making zoospore a multi-flagellate structu


place increasing the

the aseptate coenocytic structure of

methods.

The vegetative reproduction takes place by fragmentation. The thallus can break into small

septum develops at the place of breaking

fragment develops thick wall and later on develops into Vaucheria

aplanospores and akinetes

aquatic species. In

flooded. Zoospore formation takes place in

re transferred from light to darkness or

m (Fig. 2A, B). The

of a side branch. A

o it. A colourless

ed from rest of the

thin membrane and zoosporangium gets separated by a

contents of sporangium become very

place in relative position of chloroplasts and nuclei, the

zoospore. Opposite to

ucture. A terminal


aperture develops in zoosporangiu

aperture in morning hours (Fig. 2 C

Each zoospore is large yellow green, oval structure. It has a central vacuole

sap and may be traversed by cytoplasmic strands. The

towards the walls and chromatophores towards vacuoles. Two flagella arise opposite to each

nucleus. This part of cytoplasm can be regarded equivalent to one zoospore.

Fritsch (1948) regarded th

number of biflagellate zoospores h

According to Greenwood,

and whiplash type. The shorter fl

zoospore. The flagellar bases are u

According to Greenwood e

posterior region of the zoospores.

bodies and plastids are present i

zoospores.

The zoospores swim in w

significant period of rest. The zo

secrete thin walls (Fig. 2 E, F).

vegetative condition.

The two tube like outgrowt

elongates, branches to form colou

tubular coenocytic filament (Fig. 2


VAUCHERIA

ium by gelatinization of wall. The zoospore is

C, D).

Each zoospore is large yellow green, oval structure. It has a central vacuole

by cytoplasmic strands. The protoplasm outer to vacuole has many nuclei

chromatophores towards vacuoles. Two flagella arise opposite to each

nucleus. This part of cytoplasm can be regarded equivalent to one zoospore.

his kind of zoospore as compound zoospore or

have failed to separate from one another.

Manton and Clarke (1957) the flagella of a pa

flagellum of each pair is directed towards the an

united together in pairs and are firmly attached to

et. al (1957), there is large anterior vacuole and

Mitochondria are present in the peripheral layer

in the cytoplasm. Chlorophyll has also been

water for 5-15 minutes and germinate withou

zoospores get attached to the substratum, with

The chromatophores move outwards and nucl

owths develop in opposite directions. One of the

urless lobed holdfast and the other outgrowth fo

2 G, H).


s liberated through

Each zoospore is large yellow green, oval structure. It has a central vacuole which has cell

protoplasm outer to vacuole has many nuclei

chromatophores towards vacuoles. Two flagella arise opposite to each

or synzoospore as a

pair are heterokontic

anterior end of the

o the tip of nuclei.

and small ones in the

r of cytoplasm. Fat

reported from the

ut undergoing any

hdraw flagella and

uclei inwards as in

he two outgrowths

forms yellow-green


(b) By Aplanospores:

Aplanospores are commonly observed in species. V. geminata, V. uncinata

species V. pitoboloides. The aplanospores are generally

Aquatic species form aplanspores under unfavorable condition of drought.

are non-motile asexual spores formed in special

aplanospores are produced singly in cells at the terminal end of the short lateral or terminal

The protoplasm of aplanosporangium gets

aplanospore which is thin walled. In V.

apical pore formed by gelatinization.

In V. uncinata aplanospores are spherical and are liberated by rupture of

The formation and structure of aplanospores and

flagella. The aplanospores soon after liberation germinate into new thalli (Fig. 3D).


VAUCHERIA

Aplanospores are commonly observed in species. V. geminata, V. uncinata

species V. pitoboloides. The aplanospores are generally formed by terrestrial species.

Aquatic species form aplanspores under unfavorable condition of drought.

motile asexual spores formed in special structures called aplanosporangia (Fig. 3 A

produced singly in cells at the terminal end of the short lateral or terminal

The protoplasm of aplanosporangium gets metamorphosed into single

aplanospore which is thin walled. In V. germinate aplanospores are oval and are liberated from

gelatinization.

aplanospores are spherical and are liberated by rupture of the spo

The formation and structure of aplanospores and zoospores is similar except that the zoospores lack

aplanospores soon after liberation germinate into new thalli (Fig. 3D).


Aplanospores are commonly observed in species. V. geminata, V. uncinata and in marine

formed by terrestrial species.

Aquatic species form aplanspores under unfavorable condition of drought. The aplanospores

structures called aplanosporangia (Fig. 3 A-C). The

produced singly in cells at the terminal end of the short lateral or terminal branch.

metamorphosed into single multinucleate

aplanospores are oval and are liberated from

the sporangial wall.

zoospores is similar except that the zoospores lack

aplanospores soon after liberation germinate into new thalli (Fig. 3D).


(c) By Akinetes:

Akinetes are thick walled structures

low temperature. The akinetes have been commonly

uncinata.

The akinetes are formed on the terminal part of lateral branches where

to the tips followed by cross-wall formation (Fig. 4).

are called akinetes or hypnospores.

The akinetes by successive divisions may form numerous thin walled bodies

When many akinetes remain attached


VAUCHERIA

Akinetes are thick walled structures formed during unfavorable conditions

low temperature. The akinetes have been commonly observed in V. geminata, V. megaspora and V.

The akinetes are formed on the terminal part of lateral branches where protoplasm migrates

wall formation (Fig. 4). These multinucleate, thick walled segments

hypnospores.

The akinetes by successive divisions may form numerous thin walled bodies

When many akinetes remain attached to the parent thallus, the thallus gives the appearance of


formed during unfavorable conditions like drought, and

observed in V. geminata, V. megaspora and V.

protoplasm migrates

These multinucleate, thick walled segments

The akinetes by successive divisions may form numerous thin walled bodies called cysts.

thallus gives the appearance of


another alga Gongrosira.

Hence this stage of Vauch

akinetes and cysts develop into n

submerged parts of thallus develop

akinetes.

(iii) Sexual Reproduction in Vaucheria:

In Vaucheria sexual reproduction is of advanced oogamous type. The male

organs are antheridia and oogonia, respectively.

Majority of the freshwater species are monoecious or homothallic while

dichotoma, V. litorea and V. mayyanadensis are

of arrangement of antheridia and oogonia in homothallic species. The position, structure and

of antheridia are of taxonomic importance in Vaucheria.

The common patterns of arrangement of sex organs are as

(a) Antheridia and oogonia develop close to each other on

(b) The antheridia and oogonia are borne on special side branches with

and a number of lateral oogonia (Fig.

In V. hamata the reproductive branches bear a median terminal

oogonia, one on either side of antheridium.

In V. geminata and V. terrestris the sex organs are produced at the ends of

branches with a terminal antheridium and a group of oogonia

unilateral when they are arranged

sides of the filament.

(c) Antheridia and oogonia are borne on adjacent branches (Fig.


VAUCHERIA

heria is called Gongrosira stage. During favoura

new thalli. Randhawa (1939) has reported that

op sex organs whereas exposed parts of thallus

Vaucheria:

In Vaucheria sexual reproduction is of advanced oogamous type. The male

are antheridia and oogonia, respectively.

Majority of the freshwater species are monoecious or homothallic while some species like V

dichotoma, V. litorea and V. mayyanadensis are dioecious or heterothallic. There are different types

heridia and oogonia in homothallic species. The position, structure and

of antheridia are of taxonomic importance in Vaucheria.

The common patterns of arrangement of sex organs are as follows:

Antheridia and oogonia develop close to each other on the filament at intervals (Fig. 5 A

The antheridia and oogonia are borne on special side branches with a terminal antheridium

and a number of lateral oogonia (Fig. 5D).

In V. hamata the reproductive branches bear a median terminal antheridium and two

oogonia, one on either side of antheridium.

In V. geminata and V. terrestris the sex organs are produced at the ends of

branches with a terminal antheridium and a group of oogonia (Fig. 5D). The sex organs are

unilateral when they are arranged on one side of the filament or bilateral when they are on both

Antheridia and oogonia are borne on adjacent branches (Fig. 5E).


able conditions the

in V. uncinata the

form brick shaped

In Vaucheria sexual reproduction is of advanced oogamous type. The male and female sex

some species like V

dioecious or heterothallic. There are different types

heridia and oogonia in homothallic species. The position, structure and shape

the filament at intervals (Fig. 5 A-C).

a terminal antheridium

antheridium and two

In V. geminata and V. terrestris the sex organs are produced at the ends of the lateral

(Fig. 5D). The sex organs are

of the filament or bilateral when they are on both


Structure and Development of Antheridium:

The mature antheridia may be cylindrical, tubular, straight

antheridium is separated from main filament by a septum. The

stalk) arising directly from main branch

branch the antheridia are situated on androphore V. synandra.

The young antheridium is usually green in colour. It contains cytoplasm,

chloroplasts. The mature antheridia are yellow and contain

antherozoids are liberated through


VAUCHERIA

Structure and Development of Antheridium:

The mature antheridia may be cylindrical, tubular, straight or strongly

antheridium is separated from main filament by a septum. The antheridia can be sessile (without

stalk) arising directly from main branch e.g., V. civersa. The antheridia may be placed high on the

on androphore V. synandra.

The young antheridium is usually green in colour. It contains cytoplasm,

chloroplasts. The mature antheridia are yellow and contain many spindle shaped antherozoids. The

antherozoids are liberated through a terminal pore e.g., V. aversa or through many pores e.g., V.


or strongly curved. The

antheridia can be sessile (without

e.g., V. civersa. The antheridia may be placed high on the

The young antheridium is usually green in colour. It contains cytoplasm, nuclei and

many spindle shaped antherozoids. The

ore e.g., V. aversa or through many pores e.g., V.


debaryana

In monoecious species the antheridium arises as a small bulging or lateral

with or before the oogonium development (Fig. 6A). Many

and it gets cut off from the lower part forming a septum.

The antheridium grows

antheridium and the lower part is

develop into biflagellate, yellow c

of antheridium through apical pore

Structure and Development of Oogonium:

The oogonium development starts with accumulation of

cytoplasm near the base of antheridial branch. This

“wanderplasm”. The wanderplasm enters into the outgrowth or bulging of the main filament.

This outgrowth is called as oogonial ini

Large amount of cytoplasm and nuclei enter into oogonia, making it a large


VAUCHERIA

In monoecious species the antheridium arises as a small bulging or lateral

with or before the oogonium development (Fig. 6A). Many nuclei along with cytoplasm enter into it

part forming a septum.

and becomes high curved structured, its up

stalk. The nuclei of antheridium get surrounded

coloured antherozoids The antherozoids are libe

e shortly before day break (Fig. 6D-1).

Structure and Development of Oogonium:

The oogonium development starts with accumulation of colourless multinucleate mass of

cytoplasm near the base of antheridial branch. This accumulated cytoplasm has been termed as

wanderplasm enters into the outgrowth or bulging of the main filament.

This outgrowth is called as oogonial initial.

Large amount of cytoplasm and nuclei enter into oogonia, making it a large


In monoecious species the antheridium arises as a small bulging or lateral outgrowth along

nuclei along with cytoplasm enter into it

pper part is main

d by cytoplasm and

erated from the tip

multinucleate mass of

accumulated cytoplasm has been termed as

wanderplasm enters into the outgrowth or bulging of the main filament.

Large amount of cytoplasm and nuclei enter into oogonia, making it a large globular


structure called as oogonium (Fig. 6 B

branch by the development of septum

The nucleus of oogonium with protoplasm develops into a single egg.

The mature oogonia are globose, obovoid, hemispherical or pyriform in

may be sessile or stalked structure. The protoplast of

septum formation.

The entire protoplasm with single nucleus makes a central spherical mass

or ovum. In mature oogonium a distinct vertical or

beak develops a colourless receptive spot. A pore develops just opposite to receptive spot (Fig. 6 F).

Fertilization:

The oogonium secretes a gelatinous drop through a pore near the beak. A

liberated antherozoids stick to the drop. Many

antherozoids strike violently, fall

enters into the oogonium.

After its entry the membrane develops at the pore to stop the further entry

The male nucleus increases in size and fuses with the egg

zygote secretes a thick 3-7 layered wall

chromatophores degenerate and lie in the centre of the cell.

Germination of oospore:

The oospore undergoes a period of rest before germination. During

oogonial wall disintegrates and the oospore is

filaments.

Although the exact stage at which the reduction

clear, it is believed that reduction division occurs in first

oospore (Fig. 7 A-D). The oospore


VAUCHERIA

structure called as oogonium (Fig. 6 B-E). As the oogonium matures, it gets separated from main

branch by the development of septum at its base. The mature oogonium is uninucleate structure.

oogonium with protoplasm develops into a single egg.

The mature oogonia are globose, obovoid, hemispherical or pyriform in shape. The oogonia

may be sessile or stalked structure. The protoplast of oogonium is separated from main filament by

The entire protoplasm with single nucleus makes a central spherical mass

or ovum. In mature oogonium a distinct vertical or oblique beak develops in apical part. Opposite to

receptive spot. A pore develops just opposite to receptive spot (Fig. 6 F).

The oogonium secretes a gelatinous drop through a pore near the beak. A

liberated antherozoids stick to the drop. Many antherozoids push into the oogonium. The

back and push forward again and fall back. Only one antherozoid

After its entry the membrane develops at the pore to stop the further entry

e nucleus increases in size and fuses with the egg nucleus to make diploid zygote. The

7 layered wall and is now called as oospore (Fig. 6 G

and lie in the centre of the cell.

The oospore undergoes a period of rest before germination. During favourable season the

oogonial wall disintegrates and the oospore is liberated. The oospore germinates directly into new

Although the exact stage at which the reduction division takes place in

clear, it is believed that reduction division occurs in first nuclear division in the germinating

D). The oospore germinates to make haploid thallus of Vaucheria.


matures, it gets separated from main

is uninucleate structure.

shape. The oogonia

separated from main filament by-

called as oosphere

oblique beak develops in apical part. Opposite to

receptive spot. A pore develops just opposite to receptive spot (Fig. 6 F).

The oogonium secretes a gelatinous drop through a pore near the beak. A large number of

push into the oogonium. The

back and push forward again and fall back. Only one antherozoid

After its entry the membrane develops at the pore to stop the further entry of antherozoids.

nucleus to make diploid zygote. The

and is now called as oospore (Fig. 6 G-I). The

favourable season the

liberated. The oospore germinates directly into new

division takes place in Vaucheria is not

nuclear division in the germinating

germinates to make haploid thallus of Vaucheria.


Life Cycle of Vaucheria:

According to Williams, Hanatsche and Gross the life cycle of Vaucheria is

oospore being the only diploid structure in life cycle (Figs. 8,

aseptate, branched, tubular and coenocytic structure.

Vegetative re-production takes place by fragmentation. Asexual

zoospore in aquatic species and by

The zoospore is large multi flagellate structure and is supposed

Synzoospore.

The sexual reproduction is advanced oogoinous type, the male and female

antheridia and oogonia. Most of the species are homothallic,

fertilization, a diploid zygote is formed which

The reduction division takes place in oospore during germination and an haploid thallus is formed

(Fig. 8, 9).


VAUCHERIA

ing to Williams, Hanatsche and Gross the life cycle of Vaucheria is

oospore being the only diploid structure in life cycle (Figs. 8, 9). Vaucheria thallus is haploid. It is

coenocytic structure.

production takes place by fragmentation. Asexual reproduction takes place by

zoospore in aquatic species and by aplanospores in terrestrial species.

The zoospore is large multi flagellate structure and is supposed to be compound:

The sexual reproduction is advanced oogoinous type, the male and female

antheridia and oogonia. Most of the species are homothallic, some are heterothallic. After

fertilization, a diploid zygote is formed which converts into oospore and undergoes a period of res

takes place in oospore during germination and an haploid thallus is formed


ing to Williams, Hanatsche and Gross the life cycle of Vaucheria is haplontic, the

9). Vaucheria thallus is haploid. It is

reproduction takes place by

to be compound: Zoospore or

The sexual reproduction is advanced oogoinous type, the male and female sex organs are

some are heterothallic. After

dergoes a period of res

takes place in oospore during germination and an haploid thallus is formed


ASEXUAL CYCLE

SEXUAL CYCLE


VAUCHERIA

ASEXUAL CYCLE

SEXUAL CYCLE



REFERENCES:

1. Studies in Botany by Mitra, Mitra and Chowdhury (2005) 7

2. Botany for Degree Students Part

3. https://www.biologydiscussion.com/algae/life

This information, including the figures, are collected from the

solely for academic purpose.


VAUCHERIA

Studies in Botany by Mitra, Mitra and Chowdhury (2005) 7th

Edition, Vol. I.

Botany for Degree Students Part-I ALGAE by Vashishta, Sinha and Singh (2002)

www.biologydiscussion.com/algae/life-cycle-algae/vaucheria-occurrence-

This information, including the figures, are collected from the above references and will be used


, Vol. I.

by Vashishta, Sinha and Singh (2002).

-reproduction-

above references and will be used

dr. uttam kumar kanp c1t vaucheria

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