A. niger produce colonies that are composed of white or yellow felt that is covered by dark asexually produced fungal spores. Mycelial, or threadlike, hyphae are divided by a septum and transparent. Conidiophores (asexually produced fungal spores) of A. niger usually range from 900-1600 µm in length and contain globose (globular) vesicles ranging from 40-60 µm in diameter. Each globose vesicle is completely covered with biseriate phialides which are projections from the conidiophore of A. niger. These phialides come out from brown metulae, which is the site where a conidiogenous cell is created. The phialides go through a process of blastic basipetal conidiogenesis to create globose mitospores, which have a diameter that ranges from 3 to 5 µm.