Oscillatoria princeps Vaucher ex Gomont is the type species (lectotype) of the blue green algal genus Oscillatoria. The alga is dark blue green in colour which is due to the predominance of the pigment Phycobilins i.e. phycocyanin and phycoerythrin. Individual filaments were blue green to olive green in colour. Growth takes place only by transverse division hence the trichome comprises single row of cells stacked one above the other. Cytoplasmic sheath is present which is very thin, hyaline and not well distinct.