Anabaena: Vegetative Body and Reproduction | Algae | Botany

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

Vegetative Body of Anabaena (Fig. 108):

The thallus is an unbranched, straight, circinate or irregularly contorted filament of uniform thickness throughout its entire length or slightly narrowed at the ends. Each filament consists of a trichome which is enveloped by a watery, hyaline sheath of variable thickness.

The cells of the filament are usually spherical or barrel-shaped and contain protoplasts, which are either homogeneous or granulose and filled with numerous pseudo-vacuoles. The colour of the fila­ment is variable, but usually it is grey or blue-green. There are always several intercalary heterocysts, which occur usually singly are approximate of the same shape as the vegetative cells.

Reproduction in Anabaena:

Anabaena, like Nostoc, reproduces asexually, either by the for­mation of hormogones or by means of akinetes. These akinetes develop singly or in chains, either next to the heterocysts or remote from them or in both positions. They are larger than the vegetative cells and are more or less cylindrical in shape with rounded ends.

Both Anabaena and Nostoc resemble each other so closely that it becomes very difficult to distinguish between the two. Anabaena never forms colonies of define form in which the trichomes are usually not contorted. Besides, the sheath around the trichome is extremely hyaline and gelati­nous. Nostoc, on the other hand, possesses a colony with a firm envelope, and within the colony the trichomes are very much contorted.