Penicillium  produces brush-like heads.   The stalk is called the conidiophore.  The conidiophore branches at the tip.   At the end of each  branchlet is a cluster of spore-producing cells called phialides.   A chain of spores is formed from the tip of each phialide.   The spore is called a conidium.  The spores in Penicillium often contain blue or green pigments which give the colonies on foods and feeds their characteristic colour.  As I mentioned before, it is the spores in the blue cheese that give the colour to the cheese.  The spores are only a few microns in diameter.  I wonder how many millions of spores are eaten in a serving of blue cheese. How would you figure it out?  ( hint: need a haemocytometer). Return to Penicillium