eubacteria, eubacterium, true bacteria - a large group of bacteria having rigid cell walls; motile types have flagella

class Cyanobacteria, class Cyanophyceae, Cyanophyceae - photosynthetic bacteria found in fresh and salt water, having chlorophyll a and phycobilins; once thought to be algae: blue-green algae

nostoc - found in moist places as rounded jellylike colonies

trichodesmium - large colonial bacterium common in tropical open-ocean waters; important in carbon and nitrogen fixation