They are photosynthetic and grow in many different environments.
Most cyanobacteria are free-living while others have a symbiotic relationship with plants.
Cyanobacteria reproduce by fission. This is the colonial form of nostoc. Here the heterocyst is visible among chains of vegetative cells. The heterocyst's are resposnsible for nitrogen fixation. Picture by N. White Oscillatoria grows as long chains of cells called Trichomes.