Cladophora: Vegetative Body and Reproduction | Algae | Botany

In this article we will discuss about the vegetative body and reproduction of cladophora.

Vegetative Body of Cladophora:

The vegetative body is a much-branched thallus which remains attached to the substratum by long rhizoidal branches, many of which develop adventitiously from several cells near the base of the thallus. Each branch is made up of a row of elongated cylindri­cal cells joined end to end. A branch always arises as a lateral out­growth from the upper end of a cell situated towards the apical portion of the filament.

Each cell consists of a stratified cell wall made up of an inner cellulose layer, a middle pectic zone and an outer chitinous layer.

The protoplast is, in most cases, multinucleate and the cytoplasm appears in the form of a primordial utricle surrounding a central vacuole. As regards the nature of the chloroplast, there is still much difference of opinion among the algologists.

Possibly, the chloroplast is fundamentally a parietal reticulate structure with in­ward processes and numerous scattered pyrenoids. According to the most recent view, however, the mature chloroplast is regarded to be composed of numerous discoid chloroplasts with pyrenoids.

Reproduction in Cladophora:

Cladophora reproduces by vegetative, asexual and sexual me­thods. In some species during vegetative reproduction the erect por­tion of the thallus dies back, while the rhizoidal system persists. Many of the cells of the rhizoid become swollen and assume pear-shaped form. These thick-walled cells usually develop from un­branched rhizoidal branches.

After a period of dormancy and un­der favourable conditions, these cells give rise to new erect fila­ments. This is an instance of akinete-formation without dissocia­tion of the branches. In some cases, cells of the rhizoids get dissociated and each cell can give rise to a new thallus.

Asexual reproduction takes place by means of biflagellate or quadriflagellate zoospores formed by the cleavage of the proto­plasts of vegetative cells of the younger apical filaments in base-petal succession. Before the formation of zoospores, the nuclei multiply by divisions and in some species it has been recorded that meiosis takes place at this stage.

At the distal end of the mother cell a pore is formed through which zoospores escape singly. Each zoospore ultimately develops into a germling, which develops into two branches, one of which gives rise to the erect portion, the other to the rhizoidal system.

Sexual reproduction takes place by means of biflagellate game­tes. The modes of formation and liberation of gametes are much the same as those of the zoospores. Certain species are definitely heterothallic and the fusing gametes, belong to different thalli. Re­production is isogamous. After fusion a zygote is formed, which directly develops into a diploid plant.

In some species, when conjugation fails, parthenospores are produced directly from the gametes. Each parthenospore is hap­loid, and, on germination, gives rise to the thallus of the same generation. In some species of Cladophora there is an alternation of dip­loid asexual generation with a haploid sexual generation, which is morphologically alike.