Anabaena Azollae is a small filamentous phototrophic cyanobacteria generally seen as a multicellular organism with two distinct, interdependent cell types. The first is a small, circular, photoautotrophic “vegetative” cell that performs oxygenic photosynthesis and is typically blue green in color. The second is a heterocyst; a larger, paler, more homogenous cell produced by Anabaena to fix atmospheric nitrogen. A. Azollae, although it can exist on it’s own, is usually found within ovoid cavities inside the leaves of the water fern Azolla. Azolla (also known as mosquito fern, duckweed fern, or fairy moss) is a genus of common waterfern whose small leaves accumulate on the surface of bodies of water creating mats.