Nostoc: Vegetative Body and Reproduction | Algae | Botany

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

Vegetative Body of Nostoc (Fig. 107):

The thallus is an unbranched, contorted filament with a defi­nite-gelatinous sheath. Usually, several filaments occur in densely inter-woven masses and always remain embedded within a film of gelatinous envelope. Each cell of the filament is spherical, barrel-shaped, or more or less cylindrical in shape.

The cells of the fila­ment increase in number by cell divisions in parallel planes. During divisions, they nearly separate, round off and become tangent to one another giving rise to a filament resembling a string of beads.

The cell structure is more or less similar to those of other Myxo­phyceae. The characteristic feature of each filament is the pre­sence of heterocysts, which are usually intercalary but may be terminal in position.

Reproduction in Nostoc:

Nostoc reproduces asexually either by fragmentation, or by the formation of akinetes. A filament seems to break off easily, next to the heterocyst, forming short filaments called hormogones.