1. CH.(6)
By: Raghdah A. Malibari
2012 - 2013

2. Heterocyte and akinete – producing cyanobacteria

3. Nostoc
Habitat
Primarily occurs in terrestrial habitat.
Association with fungi in lichens and with some
bryophytes and vascular plants.
Moist rocks and cliffs.
 Alkaline soil.
In wet meadows.
At the edges of shallow lakes.
Cellular structure
Bent or naked filaments of round cells are held
in a firm mucilaginous matrix to form colonies.
The sheaths colored by yellow, brown or black.
Transiently motile hermogonia are produced
these typically have heterocytes at the ends.
Characteristics
Nostoc is frequently abundant in flooded rice
paddies where it contributes to the fertilization of
some 2 million hectares.

4. Anabena
Habitat
Primarily planktonic in fresh waters and
marine waters such as the Baltic Sea
some forms can be nuisance bloom formers
and toxin producers.
Cellular structure
Consist of filaments of spherical cells
resembling in a mucilaginous matrix .
Molecular phylogenetic analyses indicate
that Anabaena is not monophyletic group
separated into multiple classes.

5. Aphanizomenon
Habitat
Occurs in the Baltic Sea and in eutrophic inland water.
Cellular structure
Consist of distinctive aggregations of filaments (so
large as to be visible).
Molecular phylogenetic within Anabaena as the
Aphanizomenon.
 May not be monophyletic.
Characteristics
Aphanizomenon that which makes itself invisible.
Large blooms may form in the Baltic Sea and in
eutrophic inland waters.

6. Cylindrospermum
Habitat
Occurs in freshwaters including soft, acid
lakes.
Forming dark green patches on submerged
vegetation and on moist soil.
Cellular structure
Filaments of vegetative cells ( square or
rectangular cells).
 Heterocyte at one end are enclosed in loose
mucilage.
 A large ,highly or nemented akinete may
develop from the lowermost vegetative cell.

7. Cylindrospermopsis
Habitat
Plaktonic bloom-former in eutrophic temperate.
 Tropical freshwater around the world.
Cellular structure
Rectangular cells occur in linear or coiled
filments having a basal heterocyte.
Akinetes may form basally.
 If akinetes are not present , correct species
identification may be difficult.
Characteristics
 Important nitrogen – fixing.
C.Raciborskii this species produces the
hepatotoxin cylindrospermopsin
caused
poisoning.

8. Tolypothrix
Habitat
Plaktonic.
Entangled among submergent vegetation in
freshwater lakes (soft or acidic water ).
Cellular structure
Filaments are enclosed in a sheath of variable
consistency .
 Highly false branched usually at a heterocyte (
single false and sometimes double false branches
occur).
Characteristics
The frequency of false branching gives these algae a
woolly appearance.

9. Scytonema
Habitat
Forms dark tufted mats in masses of other algae.
 Vegetation in lakes.
 On terrestrial surfaces ( stones , wood and soil ).
Cellular structure
Often double false branches occur , this result has
been interrupted by death of a cell .
 Less commonly by heterocyte differentiation.
 Heterocyte wall may be darkly pigmented.
 Sheath is tough and sometimes clearly layered (
colored brown or orange ).
Characteristics
It is a phycobiont in several orders of lichen.

10. Gloeotrichia
Habitat
Occurs in freshwater habitat attached to
submerged substrate.
Cellular structure
Akinetes occur adjacent to basal heterocytes
( sometimes appearing in chains).
Characteristics
Gloeotrichia colonies often detach from
substrate , becoming planktonic.
 Growths can reach bloom properations.

11. True – branching cyanobacteria

12. Stigonema
Habitat
Moist rocks.
 Soil.
Some species are aquatic , attached to submerged
wood or other algae.
 Form tufted mats or cushions on submerged
portions of lake macrophytes.
Cellular structure
The filaments are more than one cell in width as
(multiseriate or pluriseriate).
 Are true-branched.
Characteristics
 The primary phycobiont in certain lichens and is
associated with boreal mosses.
 Contributes to nitrogen availability.

13. Raghdah A. Malibari