Lee Kong Chian Natural History Museum

Anabaena sp. (Bory) ex Bornet & Flah., 1888

Kingdom:Protista
Phylum/Division:Cyanophyta
Class:Cyanophyceae
Order:Nostocales
Family:Nostocaceae
Genus:Anabaena
Status:Common

Description

The trichomes are unbranched, straight or coiled. The gelatinous sheaths surrounding the trichomes are generally watery such that they are not apparent unless demonstrated by special methods. The cells are spherical to  barrel-shaped with constrictions at the cross-walls. There are numerous heterocysts that are ellipsoidal and larger than the vegetative cells. Akinetes are larger still, cylindrical and with rounded ends.

Read more about the Nostocales order.
Read more about the Nostocaceae family.

Distribution

This is a cosmopolitan genus that occurs primarily in freshwater.

Locality Map

General Biology

Mainly freshwater, although a few species occur in the marine environment. Anabaena azollae occurs as a symbiont of inside the leaves of the freshwater fern, Azolla.

Life Cycle

Akinetes can survive desiccation and eventually germinate into a new filament.

Ecological Role

Increases the fertility of the soil/water via the action of the heterocysts in fixing free nitrogen.

Human Uses

Anabaena azollae is used in association with the water fern Azolla as an alternate source of nitrogen in wet rice cultivation. This is because the alga has the ability to fix atmospheric nitrogen, providing nitrates to the crop. Generally, the water fern is grown during the fellow period of rice cultivation. The fern can also be used as a green manure in the cultivation of taro (Colacasia esculanta) or wheat (Triticum spp.).

References

Bold, H. C., C. J. Alexopoulos & T. Delevoryas, 1987. Morphology of plants and fungi. Harper & Row, New York. (5th ed.). 912pp.

Prud’homme van Reine, W. F. & G. C. Trona Jr. (eds.), 2002. Plant resources of South-East Asia No. 15(1). Cryptogams: Algae. Prosea Foundation, Borgor, Indonesia. 318 pp.

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