Reproductive Structures of Vaucheria (With Diagram) | Algae

In this article we will discuss about the asexual and sexual reproductive structure of vaucheria.

Asexual Reproduction of Vaucheria:

Various means of asexual reproduction are:

(a) Zoospores,

(b) Aplanospores,

(c) Hypnospores,

(d) Cyst formation.

Zoospore:

1. Zoospore is formed singly in the zoosporangium, formed in the terminal part of the thallus (Fig. 31).

2. Zoosporangium is a club-shaped swollen structure separated from rest of the thallus by a septum.

3. The protoplasm of the zoosporangium is accumu­lated, the nuclei come towards outer side of the chloroplasts and the central vacuole disappears. The complete structure becomes rounded. Two flagella are formed opposite to each nucleus.

4. This multinucleated and multi-flagellated structure is known as compound zoospore or synzoospore.

5. On liberation, these synzoosporesloose their fla­gella and germinate.

Aplanospores:

1. Aplanospores are produced at the ends of the ter­minal branches known as aplanosporangia (Fig. 32).

2. Aplanospores are normally produced in the terres­trial species.

3. These are non-motile and thin-walled spores.

4. They may be rounded or elongated in shape.

5. A single aplanospore is formed in each aplanosporangium.

Gongrosira Stage:

1. Hypnospores are formed in the filament by its divi­sion into many compartments or chambers.

2. These are thick-walled spores.

3. A large amount of food material is present in these spores. Each of them germinates into new plant.

4. In some species hypnospores divide into many small structures known as cysts (Fig. 33).

5. At this stage, when hypnospores in the filament of Vaucheria have-divided into cysts, the filament resembles to another alga Gongrosira and so this stage has been termed as Gongrosira stage.

6. On liberation, these cysts germinate into new fila­ments.

Sexual Reproduction of Vaucheria:

1. It is of oogamous type.

2. Most of the species are monoecious but a few are dioecious.

3. In homothallic species, antheridia and oogonia de­velop side by side. More than one oogonia may also develop alongwith an antheridium (Fig. 34).

Antheridium:

1. It is a tubular, straight or curved and hook-like struc­ture (Fig. 35).

2. It may be green or a colourless structure.

3. At maturity it is separated from rest of the thallus by a septum (Fig. 35).

4. Many nuclei and chloroplasts are present in the antheridium when young, but at maturity it is filled up with many antherozoids.

5. Uninucleate and biflagellate antherozoids are liberated through an opening formed at the tip of antheridium.

Oogonium:

1. It is ovoid or spherical (Fig. 35) and sessile structure.

2. It is a uninucleate body with many chloroplasts. Oil is the reserve food material.

3. At maturity it is also separated from rest of the por­tion of the thallus by a septum.

4. All the contents of oogonium become rounded and form a single uninucleate egg.

5. Mature oogonium contains a short, rounded beak, through which it receives antherozoids.

6. On fertilization, zygote is formed. It is a multilayered structure.

7. Zygote germinates by forming many tubular branches.