Scytonema
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| C. Agardh ex Bornet & Flahault |
Scytonema is a genus from the tribe of cyanobacteria (blue-green algae).
description
Scytonema forms falsely branched, mostly blue-green to brown, single-row threads (diameter 8 to 70 µm) with cylindrical cells which, like all bacterial cells , contain neither nuclei nor plastids . Each thread lies in its own gelatinous sheath. The spurious branching comes about through intercalary growth. This creates a loop in the thread that breaks out of the gelatinous sheath, mostly due to the death of individual cells. This creates the two side branches typical of this species in one place. Colorless, thick-walled cells are regularly found in the threads and at their ends. These are heterocysts that are used for biological nitrogen fixation .
Reproduction
The asexual multiplication takes place by wenigzellige, capable of creeping yarn fragments, called hormogonia.
Sexual reproduction is absent in all cyanobacteria .
distribution
Scytonema lives on stones at the bottom of standing and flowing water, but also on aquatic plants. Some species survive occasional drainage of the water. Few species also live in hot springs . They can also be found on damp stones. The "ink streaks" appearing over large areas on limestone rocks in the mountains are partly formed by this genus.
Types (selection)
swell
- Karl-Heinz Linne von Berg, Michael Melkonian u. a .: The Kosmos algae guide. The most important freshwater algae under the microscope. Kosmos, Stuttgart 2004, ISBN 3-440-09719-6 .