Nostocales

Nostocales
Anabaena flos-aquae
Scientific classification
Kingdom:	Bacteria
Subkingdom:	Eubacteria
Phylum:	Cyanobacteria
Order:	Nostocales T.Cavalier-Smith
Families
Aphanizomenonaceae Elenkin Capsosiraceae (Geitler) Elenkin Chlorogloeopsidaceae (Mitra) Mitra & Pandey Fortieaceae Gloeotrichiaceae Komárek et al. 2014 Godleyaceae Hauer, Mareš, Bohunická, Johansen, & Berrendero-Gomez Hapalosiphonaceae Elenkin Nostocaceae C. A. Agardh ex Kirchner Rivulariaceae Kützing ex Bornet & Flahault Scytonemataceae Rabenhorst ex Bornet & Flahault Stigonemataceae Borzì Symphyonemataceae Hoffmann, Komárek, & Kaštovský Tolypothrichaceae Hauer, Mareš, Bohunická, Johansen, & Berrendero-Gomez
Synonyms
Hormogonales

The Nostocales is an order of cyanobacteria containing most of its species. It includes filamentous forms, both simple or branched, and both those occurring as single strands or multiple strands within a sheath. Some but not all members show a decrease in width from the base. Again, some but not all have heterocysts.