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Diagnostic features

Tapering, heteropolar filaments with a heterocyte at the base of each. Filament ends narrow to colourless hair-like cells.  False branching common (cf. Calothrix), with the new branch growing parallel to the previous branch initially and then diverging, and with a heterocyte at the base.  Mucilage sheath always present.

Typical habitats

Most common in good quality stony streams


Kingdom Bacteria
Phylum Cyanobacteria
Class Cyanophyceae
Order Nostocales
Family Rivulariaceae
Common name Cyanobacteria