Penicillium roquefortii. False-colour scanning electron micrograph (SEM) of conidiophores (spore bearing hyphae) of the fungus Penicillium roquefortii, seen growing on Stilton cheese. The colour and flavour of the cheese is produced by Penicillium roquefortii, the spores of which cover the surface of the blue veins in the cheese. In commercial production of Stilton cheese, the curd is pressed so as to create cracks. These cracks contain enough oxygen to support colonies of the fungi, which are introduced into the cheese. The mature penicillin fungus bears chains of spores, as seen here, each spore able to germinate a new fungus. Magnification: x375 at 6x4.5cm size.