Spirogyra is a genus of filamentous green algae of the orer Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is diagnostic of the genus. It is commonly found in freshwater areas, and there are more than 400 species of Spirogyra in the world.Spirogyra measures to around 10 to 100μm in width and may stretch centimeters long.