Penicillium is a saprophytic fungus, commonly known as blue or green mold. They are present in the soil, in the air, on decaying fruits, vegetables, meat, etc. Asexual reproduction in Penicillium takes place by unicellular, uninucleate, non-motile spores, the conidia; formed on conidiophore. A number of flask-shaped phialides or sterigmata develops at the tip of each metulae. Each sterigmatum develops at its tip a number of conidia arranged basipetally (younger one near the mother and older one away from it). During the development of conidium, the tip of the sterigma swells up and its nucleus divides mitotically into two nuclei, of which one migrates into the swollen tip and by a partition wall, the swollen region cuts off from the mother and forms the uninucleate conidium. The tip of the sterigma swells up again and following the same procedure second conidium is formed, which pushes the first one towards the outer side. This process repeats several times and thus a chain of conidia is formed. After maturation, the conidia get detached from the mother and are dispersed by wind.