CLASSIFICATION OF VAUCHERIA
Sub-division :- Algae
Class :- Xanthophyceae
Order :- Heterosiphonales
Family :- Vaucheriaceae
Genus :- Vaucheria
Species of this genus grow in aquatic as well as in terrestrial habitats. Terrestrial species occur on damp soils of gardens, lake sides, ploughed fields and form an extensive green belt on the soil surface, specially during early winters. The aquatic species also occur as a large green mat floating over the surface of water
THALLUS OF VAUCHERIA
- Thallus is unicellular, multinucleate, filamentous and branched (coenocytic).
- Filaments are profusely branched. The branching is lateral but appears dichotomous.
- Filaments are without any septation (aseptate filaments).
- If terrestrial in habitat, a few colourless rhizoidal branches are given out which penetrate soil.
- Cell wall is two layered. Outer layer is composed of pectose while inner is that of cellulose.
- In the center lies a big vacuole, continuous throughout the length of the filament.
- The cytoplasm lies between vacuole and the cell wall.
- Many small nuclei are scattered in the cytoplasm near the vacuole.
- Small chromatophores are also scattered in the cytoplasm. They are circular or elliptical in shape. Pyrenoids are absent.
- The reserve food material is in the form of small oil droplets.
GONGROSIRA STAGE OF VAUCHERIA
- This stage of asexual reproduction develops under extreme conditions of desiccation or low temperature.
- It is called Gongrosira because it looks similar to another algal member-Gongrosira.
- In this stage, filament is divided into many, short and thick-walled parts.
- Each of these parts is called akinete or cyst.
- Akinetes are thick walled and rich in oil contents.
- Akinetes occur in long chains, alternating with a part of filament.
ANTHERIDIA OF VAUCHERIA
- Filaments are mostly monoecious but a few species are dioecious.
- Sexual reproduction is oogamous.
- Male reproductive bodies are antheridia and female reproductive bodies are oogonia.
- The antheridia and oogonia are borne side by side on the same filament. Sex organs are generally sessile but a stalk-like structure is present in a few species.
- Antheridia are terminal. These are strongly curved, hook-like and cylindrical.
- Antheridia are cut off from the main filament by a transverse septum at its base.
- Protoplast accumulates towards the centre. It produces many biflagellate antherozoids.
- Antherozoids are liberated through a small pore at the tip of antheridium.
OOGONIA OF VAUCHERIA
- More than one oogonium are present at the tip of the stalks which once again branch at their tips.
- Oogonia are oval or spherical and terminate into a short beak.
- The entire protoplast forms a single oosphere.
- In younger stages, oosphere is multinucleate but at maturity it is always uninucleate.
- Near the beak, in the apical part, the protoplasm leaves a small colourless area, known as receptive spot.
- Protoplast is rich in food reserve which is in the form of oil droplets.
ZYGOTE OF VAUCHERIA
- Zygote is the result of fertilization.
- It is present inside the oogonium.
- It is a thick walled structure being made of 3-7 layers.
- The protoplast of a zygote is very dense.
- Numerous oil droplets are scattered throughout the protoplasm.
- It is considered to be a diploid structure, as such there is said to be possibility of zygotic meiosis.
- It is liberated through the oogonial beak.
- Sub-division– Algae
- Presence of a simple thallus.
- Chlorophyll present
- Cell wall made of cellulose.
- Class – Xanthophyceae
- Chromatophores yellow-green.
- Photosynthetic reserve-oil droplets.
- Motile cells with unequal flagella.
- Order – Heterosiphonaies
- Thallus multinucleate, unicellular and siphonaceous
- Family – Vaucheriaceae
- Thallus branched, filamentous,tubular and coenocytic.
- Zoospores multiflagellate.
- Sexual reproduction oogamous.
- Genus – Vaucheria
- Branching irregular or lateral.
- Sex organs without constriction at the basal septum.
This Post Has One Comment
Pingback: Algae - Definition, Characters, Classification, Example