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Diagnostic features

Unbranched filaments of short cylindrical cells in a fine sheath. Filament may glide within the sheath. Cells may be at least as long as they are wide (cf. Oscillatoria).  End cells often pointed/tapered, with a calyptra (thickened cap) on the terminal cell. Tapering may extend several cells from the end.  Heterocytes absent.  Organelles absent from the cells, but granules/vesicles common.  Forms mats that may be dark brown, green, purple or blue-green.

Typical habitats

Streams and rivers of all sorts of water quality


Kingdom Bacteria
Phylum Cyanobacteria
Class Cyanophyceae
Order Oscillatoriales
Family Phormidiaceae
Common name Cyanobacteria